Ronnie Posted May 30, 2011 Share Posted May 30, 2011 I was trying to help out a neighbor put a can of freon in his '90 model Buick today. It has 3800 engine. Everything looks like standard Reatta stuff. It has been converted to 134a. It's still cooling. Just not very well. Low side would slowly pull down to about 24-30 psi, the compressor would kick out, pressure would creep up to about 65-70 psi and the compressor would kick back in. We tried to put in a can of 134a but it wouldn't take it, even when putting the can in hot water. We tried another can and a different filler hose. Same result. Any ideas about what is going on? I'm not an A/C guy. Any help would be appreciated. Link to comment Share on other sites More sharing options...
padgett Posted May 30, 2011 Share Posted May 30, 2011 Numbers don't sound right - mine kick out at 18-20 psi - what is the high side reading ? Might have a partly blocked oriface in which case the high side will be, well, high. Ask if it ever had "leak sealer" put in. Link to comment Share on other sites More sharing options...
Guest Mc_Reatta Posted May 30, 2011 Share Posted May 30, 2011 Not being able to inspect the rig makes it hard. Padgett is correct in that the low side pressure is a high for the system to be cycling. But even at 30 psi a new can of freon should be able to power in better than half a can.Leads me to believe there is a problem with the charging rig.Are you using the conversion 134 adapters on the pressure ports or just the R12 ports?Are you using a full gauge rig or just a separate low side gauge and a separate charging hose? My best guess is the low pressure schrader valve is not getting pushed open by the charging hose connector, or if a full rig, the valve between the charging hose and the low pressure hose isn't opening. Link to comment Share on other sites More sharing options...
Ronnie Posted May 30, 2011 Author Share Posted May 30, 2011 I only have the low pressure hose. It has the 134a adapters. I'll bet you are correct about the schrader valve not opening. I intend to check it out latter today and will report back. Thanks for the tip! Link to comment Share on other sites More sharing options...
Ronnie Posted May 30, 2011 Author Share Posted May 30, 2011 Turns out the adapter was the reason freon wouldn't go in. Pushing in on the connector solved that problem. Now have 40 psi showing on the gauge when the compressor is running but the low pressure switch still keeps kicking out the compressor. Lowest vent temp at 92* ambient outside is around 69*. If I jumper the low pressure switch to keep the compressor running the vent temp will go down below 50*. I'm thinking it's time for a new low pressure switch. Do you guys think I'm right or is something else going on that I'm missing? I'm doing the labor and furnishing the parts as a way of saying thank you to an old vet but I don't want to waste my money on unneeded parts to say it. :D Any input would be appreciated. Link to comment Share on other sites More sharing options...
harry yarnell Posted May 30, 2011 Share Posted May 30, 2011 ....or the gauge is wrong.As for the 134, I look for 40# low side; 32# with R12. Link to comment Share on other sites More sharing options...
Ronnie Posted May 30, 2011 Author Share Posted May 30, 2011 ....or the gauge is wrong.As for the 134, I look for 40# low side; 32# with R12.Good point Harry. I just tried another gauge and got the same reading. Is the low pressure switch the problem? Link to comment Share on other sites More sharing options...
hinspect Posted May 30, 2011 Share Posted May 30, 2011 Just got my hard drive back online. Ronnie you live in my area. Big - Lots has R134-A on sale for $8.00 a can. I am not depending on it, as usual they may be out of stock and have the other freon blend anyway in the basement. I do not have our reatta converted and have no intetion of doing so. I stil use Freeze12 in the reatta. Converted the truck to R-134A and it does not cool nearly as well. I did not know if you were interested (and anyone else) but might be of some help. Terry Link to comment Share on other sites More sharing options...
Ronnie Posted May 30, 2011 Author Share Posted May 30, 2011 Thanks Terry! I'll check them out. I paid $14.95 plus tax at Advance and they were discounting it $1. Link to comment Share on other sites More sharing options...
Guest Mc_Reatta Posted May 30, 2011 Share Posted May 30, 2011 Yes Ronnie, sounds like the low pressure switch is not working correctly. Should not turn off the compressor until the low side gets below 20 psi. Less in the Reatta.If your sure the guage is correct and I suspect it is from your vent temp, then I'd replace the switch. Does this system have the low and high temp sensors as our Reattas do?If so, it could be a bad low temp sensor causing the cycling thinking the evaporator is as the freezing point, but your shorting out of the switch stopping the problem leads me to conclude the pressure switch is the problem.If it is the in line type as in our Reattas, let us know where you find one as someone was looking for a source for one. The ones that mount on the rear of the compressor are very common, but the inline ones we need are hard to find. Link to comment Share on other sites More sharing options...
Ronnie Posted May 30, 2011 Author Share Posted May 30, 2011 I assume it is the same as the Reatta. It's a Riviera. You select the desired temp and the system does the rest. Advance has the low pressure switch on their website. I just called and ordered one and they said it would be here tomorrow morning. Their website shows the same part number for the Reatta. Their website it a "Factory Air Switch" but it looks like right one in the photo on their website. (see below) Can't tell for sure about the connector but will know for sure tomorrow.I'll post the results of installing the new switch tomorrow. Thanks to everyone for the help!Factory Air SwitchPart No. 36668 Warranty Low Pressure A/C System Mounted Link to comment Share on other sites More sharing options...
Guest Mc_Reatta Posted May 30, 2011 Share Posted May 30, 2011 Once you get the compressor working properly, I think you'll find you are now overcharged. I'd be shooting for a low side pressure of around 30 to 32 psi, AC on full max cool, windows down, good air flow over condenser, ambient over 80 F. Link to comment Share on other sites More sharing options...
padgett Posted May 31, 2011 Share Posted May 31, 2011 People always forget to put a big fan in front of the radiator - essential both to cool properly and to keep high side pressures down. LO fan just keeps it from overpressuring. Link to comment Share on other sites More sharing options...
Ronnie Posted May 31, 2011 Author Share Posted May 31, 2011 I picked up the low pressure switch this morning from Advance Auto Parts. It fits perfectly and does the job. The car is now cooling as it should. I feel the switch lacks the quality of the original part. It is made in Taiwan and is sold by a company called "4 Seasons" of Lewisville, TX. The part number on the box is 36668. The cost is $18.99 plus tax.I appreciate the help everyone offered. Now that I see how well these systems should work I'm going to take a look at mine and see why it isn't cooling as it should. Link to comment Share on other sites More sharing options...
DAVES89 Posted May 31, 2011 Share Posted May 31, 2011 One thing that I am trying, [and so far am happy with the results] is using two blower control modules. I have one in the plenum, as it should be, [to keep foreign matter out] but not wired in. I then have another one [wired in] but ziptied to the wiring harness. The A/C seems to come on faster, especially after starting the car up after the car has been run awhile, and already is hot under the hood. Link to comment Share on other sites More sharing options...
Ronnie Posted May 31, 2011 Author Share Posted May 31, 2011 I have been investigating why my Reatta was not cooling well most of the afternoon. I added some freon to get the pressure up to 40 psi on the low pressure side just like the other car. Adding freon made it cool slightly better but nothing like it should. The vent temp gets down to about 68* with ambient being 93* here today. The problem seems to be the low side temperature sensor is kicking the compressor out after about 11 seconds before much cooling takes place. The compressor stays off about 25 seconds and then comes back on. It does the same thing if its sitting with a fan in front of the car or driving down the road. I can disconnect the sensor and jumper the connector with a 5 ohm resistor (to simulate the sensors condition before startup) and the vent temp will go down to about 45*. Feels verrrry nice and cool. However, the compressor runs all the time and never kicks out with the jumper in place. Does that tell me the sensor is bad? The sensor passes the tests in the FSM but those tests are done with the engine not running. Link to comment Share on other sites More sharing options...
Guest Mc_Reatta Posted May 31, 2011 Share Posted May 31, 2011 Ronnie, while your car is dead cold, like after sitting overnight, enter diagnostics mode.Go to BCM Data mode and call up the 3 underhood temp sensors.BD26, 27 and 28. They should all agree or be very close to each other. Let me know what they say. Link to comment Share on other sites More sharing options...
Ronnie Posted May 31, 2011 Author Share Posted May 31, 2011 I'll try that in the morning. Thanks Link to comment Share on other sites More sharing options...
Ronnie Posted June 1, 2011 Author Share Posted June 1, 2011 OK here's what the readings are this morning before starting the engine. I threw in a few extras. I checked three times and the reading always repeat within one degree.BD25 - inside temp - 31*BD26 - outside temp - 30*BD27 - hi side temp - 19*BD28 - low side temp - 12*BD32 - sun temp - 47* (the car has been in the garage all night???)Actual temp in the garage when readings were taken - 89*F.It would be nice if someone with a normally working A/C system would check their readings and post the results here for comparison. Link to comment Share on other sites More sharing options...
Guest Mc_Reatta Posted June 1, 2011 Share Posted June 1, 2011 (edited) OK, (I love the Reatta's Diagnostics!)Your data confirms what I suspected that you low side temperature sensor was faulty.Your 89 F ambient equates to 31.66 C.When dead cold no solar load, all the temp sensors should read within a few degrees of that.Your inside and outside sensors are AOK.Your low side and high side temps are way low.I won't make a determination of your sun load reading since I can't confirm what the range of that sensor is, but I'd be curious about that one too. At least it is in the good direction in that it will cause the AC to work harder not less which unfortunately your low sensor is doing.Here's what 2 of my cars are doing right now parked outside (so I do have solar loading going on): Ambient 80 F or 26.66 C (one has sun shields in place one doesn't can you guess which one?) *** *car 1*** car2BD25 39 *** 45 inside tempBD26 29 *** 29 outside tempBD27 29 *** 28 high side tempBD28 28 *** 29 low side tempBD32 59 ****64 solar load The important numbers are BD 26 thru 28 which are all within 1 degree of each other and within a couple of degrees of ambient.So Ronnie you need to get a set of high and low side temp sensors and replace your defective ones and then check your refrigerant charge level.Your low side sensor is causing you AC compressor to cycle on and off because your BCM is being lied to that your evaporator is about to freeze up when it is no where near the freezing point.When your AC is working, the BCM watches the low side temp and when it hits o C it turns the compressor off so that the evaporator coils won't freeze over, and when the low side temp climbs back up to ~ 7 C it will cycle the compressor back on to keep cooling.When you charge is on the low side this cycling will occur all the time which you can confirm by looking at BD28 as you run down the road with the AC on.You will see it go from about - 2 on one end up to ~ 10 C and back down to -2 again. If you can listen for the clutch relay, you might be able to hear it kick off at 0 and back on at 7. Hysteresis causes a little overshoot on both ends to the -2 and 10 degrees indicated.If your charge is dead on, the low side temp would stay steady at 0 C with no cycling. That is almost impossible to accomplish since there are so many variables that affect it, but if you can get it to hold steady between 0 and 4 degrees you're are optimally charged. If you are overcharged, your low side temp will be steady but be over 5 C so you are losing some cooling capability of the system. The higher the reading the more your giving up.Your 40 psi low side pressure reading indicates that you are getting your evaporator to ~ 45 F or 7 C so you are giving up some cooling capability, but it will help keep the low pressure warning from coming on when the ambient drops under 70 F or so in the fall when a lot of members report getting that message.The summer vent air temp that you can measure will always be higher than the evaporator temp since it depends on in car air temp, and the speed that the air flows thru the evaporator. The cooler the air temp and the slower it moves the more heat it can transfer to the evaporator and a lower vent temperature reading will result. Edited June 1, 2011 by Mc_Reatta (see edit history) Link to comment Share on other sites More sharing options...
Ronnie Posted June 1, 2011 Author Share Posted June 1, 2011 Thanks for all the help. It all makes sense the way you explain it. Can you tell me if the low and/or high temp sensors can be changed without loosing the freon? Do you know a source for the sensors? Link to comment Share on other sites More sharing options...
Guest Mc_Reatta Posted June 1, 2011 Share Posted June 1, 2011 The same sensor is used for the low and high side.PN 1626146 Sensor AC Refrigerant Temp.I found a 2010 post from Padgett:GMPartsDirect.com - watch out for the S&H.1626146 list $113.19 net $67.10 Air conditioner and heater - Condenser compressor and lines - Temp sensor Temp sensor 1986 - 1989Link to alternate catalog page:gmpartsdirect.com: Alternate GM CatalogBut they currently say part has been discontiued.My search of RockAuto and GM Parts Giant came up no part found.May try Jim for some. Should be able to test by measuring their resistance if not in a working system. Link to comment Share on other sites More sharing options...
Ronnie Posted June 1, 2011 Author Share Posted June 1, 2011 Do you know if the sensor can be changed without discharging the system? I really appreciate all the help. Link to comment Share on other sites More sharing options...
Ronnie Posted June 1, 2011 Author Share Posted June 1, 2011 BTW, the low temp sensor is what is preventing the system from cooling properly. I paralleled a 25 ohm resistor with the sensor and the system is cooling great and the compressor is cycling as it should. Vent temp is ~50* at 94* ambient outside. I will check in the morning and see how close I came to getting the BCM to see the correct temperature. The resistor should get me by until I can change out the sensors. Hey, if the sensor can fool the BCM so can I! LOL Link to comment Share on other sites More sharing options...
Guest Mc_Reatta Posted June 1, 2011 Share Posted June 1, 2011 I don't know if it can be replaced without discharging the system. I may be working on an empty leaking system shortly, If I do, I'll check to see if it can be or not and let you know.Your work around should keep you cool for a while, just look out for snowflakes coming out of the vents. Link to comment Share on other sites More sharing options...
Ronnie Posted June 1, 2011 Author Share Posted June 1, 2011 Thank you! Link to comment Share on other sites More sharing options...
Guest Albert Posted June 1, 2011 Share Posted June 1, 2011 the low side pressure switch does have a shreader valve under it, so it can be remove without loosing the whole charge, it will hiss a little while the pressure between the line and the switch leaks out. Link to comment Share on other sites More sharing options...
Guest Mc_Reatta Posted June 2, 2011 Share Posted June 2, 2011 Sorry to snow on your parade Ronnie, but that ain't it. The air charge sensor is in the bottom of the air cleaner housing and is used by the ECM to determine the temp of the incoming air to the engine and set up the fuel parameters.The AC temp sensor looks quite different. I examined one and it definitely does not look like it can be removed without discharging the system.TO ALL THE BONEYARD PICKERS:These AC temp sensors are apparently unobtainium.As you peruse the pickens at your favorite yards, and you come across cars with our same type AC system like other Buicks, Caddies etc. Grab the two temp sensors from the AC line running across the firewall under the cowl cover. You will need a 27 mm or 1 1/16 deep socket and ~ 5/8 open end wrench to muscle them out, or you can pull the whole orifice tube and leave the low side sensor in place. Test them by measuring the resistance between the terminals. Should be about 2.5 KOhm at ~ 80 F ambient. Link to comment Share on other sites More sharing options...
Ronnie Posted June 2, 2011 Author Share Posted June 2, 2011 You are correct Mc. I just went out and took a closer look at my sensor. The post I made about the NAPA part will be deleted to prevent misleading anyone. I'm glad the resistor trick worked or I would really be sweating. Maybe we should be looking for a Cadillac part that would interchange or could be adapted for use on our Reattas. If we don't find a source for the sensor, installing a resistor to correct the sensor error might become a common cure. Link to comment Share on other sites More sharing options...
Guest luvmy89riv Posted September 2, 2011 Share Posted September 2, 2011 Where can I get this GM #1626146 A/C temp sensor. My error code is a B111 which says the HIGH side temp sensor is bad. But I also show a history for the B112. (Low side temp sensor). Should I replace both. I read earlier in the post that they are the same part number. Can someone confirm that?Thanks alot!!!I own 2 of these beautiful 89 Rivieras. They look like twins. Ray Link to comment Share on other sites More sharing options...
Ronnie Posted September 2, 2011 Author Share Posted September 2, 2011 Getting a code B111 doesn't always mean the sensor is bad. It is telling you the reading is out of the normal range. You need to follow the flow charts in the Field Service Manual section 8D2-7 to troubleshoot the problem. If you could find them, replacing the sensors may not cure the problem or the code B111 or B112. I don't think the sensors are available new. Link to comment Share on other sites More sharing options...
Guest luvmy89riv Posted September 2, 2011 Share Posted September 2, 2011 Wow. A very fast reply. Thanks Ronnie.Here is my issues with this car. Only when I have the A/C on, the cooling fan in front of the radiator and the A/C compressor clutch turns on and off intermittently. 6 seconds ON and then 10 seconds OFF. It just keeps doing that all of the time that the A/C on. I believe the B111 code says 'current'. B112 code says history. Any chance that just charging the freon system will fix this? I am wondering if I will have the same issue, if not fixed properly now, when it gets cold out and I have to use the heater. Any idea? Any chance that a new 4-Seasons low cut-out Pressure switch will help anything? For $20, I might put one in before I charge the system. Thank you very much.Ray Link to comment Share on other sites More sharing options...
Guest luvmy89riv Posted September 3, 2011 Share Posted September 3, 2011 If I was going to any salvage yards, what years and models might I have the best luck in finding with these parts? Cadillacs? Buicks?Thanks again. Link to comment Share on other sites More sharing options...
Ronnie Posted September 3, 2011 Author Share Posted September 3, 2011 Wow. A very fast reply. Thanks Ronnie.Here is my issues with this car. Only when I have the A/C on, the cooling fan in front of the radiator and the A/C compressor clutch turns on and off intermittently. 6 seconds ON and then 10 seconds OFF. It just keeps doing that all of the time that the A/C on. I believe the B111 code says 'current'. B112 code says history. Any chance that just charging the freon system will fix this? I am wondering if I will have the same issue, if not fixed properly now, when it gets cold out and I have to use the heater. Any idea? Any chance that a new 4-Seasons low cut-out Pressure switch will help anything? For $20, I might put one in before I charge the system. Thank you very much.RayWelcome to the forum Ray!The AC fan cutting off when the AC compressor cycles sounds odd (I don't think my Reatta does that) but other than that it just sounds like you are low on freon to me. No need to change the Low Pressure Switch (if that is what you are referring to) just because you plan to add freon. It can be changed anytime without losing the freon charge. I would add freon and go from there if it still gives problems. Link to comment Share on other sites More sharing options...
Guest luvmy89riv Posted September 3, 2011 Share Posted September 3, 2011 Thanks again Ronnie. I hope this is just as simple as adding Freon. I will be very happy but also very mad at myself thinking that this was a bigger issue and driving around with only 50% cooling power and living in Wichita, Kansas where we have broken records of all time history having over 51 days of high temps of 100 + degree days this summer. OMGTomorrow morning I am taking it (Riv2) in to get looked at and charge up the freon. I may be back here tomorrow night. :eek:Ray Link to comment Share on other sites More sharing options...
padgett Posted September 3, 2011 Share Posted September 3, 2011 Just as a data point, happened to drive continuously for about 30 miles yesterday and was seeing 34-38F at the center outlet of the 88 on a 90+ day on AUTO/AUTO. Think finally got the charge right.Strange how everyone complains about Florida when on the average it seems to be cooler than the rest of the country. Must be the humidity. Link to comment Share on other sites More sharing options...
Guest luvmy89riv Posted September 4, 2011 Share Posted September 4, 2011 Well, it was not the freon. Plenty in the system and something still setting the A/C clutch and fan to cycling on for 6 seconds and then off about 10 seconds over and over again. I believe the technician said the High and low pressure temp sensors were saying 190 degrees F the other number was -40 F. He did not think it was the temp sensors that were wrong. He thought that maybe the BCM could be bad. What do you all think? Test numbers were taken after he started the car and was listening to the fan and clutch turn on and off for a while.Thank goodness, I just happen to have the original BCM that came out of that car 7 years ago. I switched BCM's with a salvaged 89 Riv years ago because I wanted to have the Compass feature in the car. Any thoughts out there? Bad BCM? Thanks again,RAY Link to comment Share on other sites More sharing options...
Ronnie Posted September 4, 2011 Author Share Posted September 4, 2011 Have you checked these readings before starting the car first thing in the morning? The readings I got (below) verified that I had a bad temperature sensor. All the readings should be pretty close to the same as were the results that McReatta got with his car.Here's what the readings are this morning before starting the engine. I threw in a few extras. I checked three times and the reading always repeat within one degree.BD25 - inside temp - 31*BD26 - outside temp - 30*BD27 - hi side temp - 19*BD28 - low side temp - 12*BD32 - sun temp - 47* (the car has been in the garage all night???)Actual temp in the garage when readings were taken - 89*F. Link to comment Share on other sites More sharing options...
Guest luvmy89riv Posted September 4, 2011 Share Posted September 4, 2011 No. Not sure how to check the numbers. I know how to get into the service mode, but not sure how get thru the screens once in. If you can give me the directions, I am sure I can do it tomorrow morning. Thanks,Ray Link to comment Share on other sites More sharing options...
Ronnie Posted September 4, 2011 Author Share Posted September 4, 2011 Instructions are in this booklet:Computer Diagnostic Instructions - 1988/1989*-*ReattaOwner.comTo be more specific:Diagnostics Instructions Page 8*-*ReattaOwner.com Link to comment Share on other sites More sharing options...
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