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Another A/C question.....


Guest Seriousmojo

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Guest Seriousmojo

Hello....just signed up today,so I'm a newbie..... I have been reading the posts for a cpl weeks and they have been very helpful. My question is about the a/c in my 1991 reatta....I cannot get it tio stay on. I have followed the advice from several members,but nothing seems to work..... I have disconnected the battery to reset codes. That helped a little,but when turned back on,a/c didn't work again. Even tried jumping the low pressure switch to get the compressor to run....Nothing. It has been converted to 134 and has a good charge acording to a friends guages,and for the short time it ran it put out really cold air.......I have seen in the forum about cleaning the switches in the control panel . Now even tho the blower comes on,could it still be the switch? Any help would be greatly appreciated....

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Guest Seriousmojo

ok.....an update on the a/c..........it will come on and work (but I'm sure it needs more coolent) if the temp is under 80 or so. Drove it to work last night and it worked all the way.....Today I drove it ,it's a little over 90 today....it ran for about 20 mins and shut down......I have one fan that I found out is not working..(the big fan on the inside of the engin bay) could the fan have anything to do with this? ....Thinking about selling this car also........... If anyone is interested,I'll try to post some pics........Dave

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If you are not getting the fans running this could result in effectively a blocked input which will make the high side pressure go through the roof - high enough (think BD27 will read around 98C) and the compressor will be shut down. It matches the symptoms. You need the fans both working.

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Guest Seriousmojo

Thanks padgett......got to thinking that may have something to do with it......I'll check it tomorrow morn,supposed to cool off some tonite.........Thanks again........Dave

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Guest Seriousmojo

Ok.....got a new fan today (inside radiator fan) hooked it up,and the a/c started right up...got nice and cool for a 98 % day.....drove around for about 30 mins and it was still working great.The temp stayed down on the car at about the 12 o"clock mark...then it stopped ! can't get it to turn back on even after disconnecting the neg batt terminal for an hour or so.....what could it be now? lol didn't mess with it anymore yet....like I said,it's 98% here....any more Ideas? Guess I should clean the switches next....

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Guest Seriousmojo

Ok.... heres a good one....the a/c hasn't been messed with for a few days,too hot to work on it. So last night I drove the car to work..Had the a/c switched on even tho it waswn't working just to get some air into the car. Was around 80.....hit the gas to pass another car.....WHAM...the a/c turned on and in about two mins it was so cold I had to turn it down....checked it out on the way home this morn and it is still working....Is there a vac switch on it somewhere? Something happened............I messed with pullin up the codes yesterday,but it was too hot to work with it much.Gonna try to get back to that today.......

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Been playing with several over the last few days and did find a common factor. With the correct charge BD28 does not go below zero to +2 degrees C at 90F. Slightly low (50F at outlet) willl drop to -1 or -2. Quite low, 60F at outlet, will drop to -5 -6 and be cycling.

There does seem to be some variation in sensors but by -7C it will force a cycle.

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Guest Seriousmojo

My BD28 was as far as I can tell is 60 and the BD27 reads 70.....I'm not up to speed on the code stuff because most of my cars are older and have no electronics...so I'm having to play catch up.....to be honest,I'm supprised I got the codes to come up...lol Dave

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Guest Seriousmojo

Ok I was just reading another post and a HVAC programmer was mentioned......what exactly does this unit control ? and could it be part of my problem ? I am getting ice cold air out on the highway,but the a/c gets warm if I'm driving around town.....but picks back up at highway speeds....... Dave

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OK in general two things cause cold at speed and warm when slow. The first is insufficient air flow through the condensor which will cause the BD27 to go through the roof at low speeds. The second is an old compressor with seals that leak internally. Think of it as poor compression. It must turn fast to move enough refrigerant.

Some warming at a stoplight is common, why I kick the idle in drive up to 725 from 650 & reset the fans to come in a lot sooner. Warming a lot could be a worn out compressor - can tell with a good set of gauges or BD27 will be low at idle and pick up at speed.

Or some combination - why hvac is an art form.

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Guest Richard D

Padgett is correct, I could get cooling until about 11:00 AM when the car interior goes over 100, the lowest vent temp I could get while crusing was 73 degrees, stopped at a light it would go up to 89/90. Turns out my car had the original compressor with over 140,000 miles on it. I am having a new compressor, acumulator and orifice tube today. They were not able to finish it so I will have to wait until Monday. Will post results.

Richard

PS. Keeping it R-12, I found a small stash.

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Guest Seriousmojo

Ok I think maybe I didn't word my last post right.... The air is cold around town...I drove around for an hour in stop and go.........I got on the interstate and I guess under constant speed it got colder....my PT Cruiser will do the same thing.......when I get off the interstate and drive around town,it gets not warm,but hot ...like the heater is on........I was reading in another post about the HVAC vaccum control.........is it possible that I have a bad vaccum pot that is letting the heater/air door switch back to heat? Or maybe even a leaking vaccum hose somewhere in all the mess........Dave

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Guest Seriousmojo

ok either I am blind,crazy or both.........first I changed some vac lines (quite a few were almost decomposed and collapsed.........car idles better and seems to run a little better........a/c stays cold longer..when it runs.........now for the crazy part......I CAN'T FIND ANY CONDENSOR COILS ON THE RADIATOR !!!!!!!!!!!.....it's a 91......I found a oil cooler coil....but no condensor..........WHAT"S UP ?....am I missing something ? ......I am baffled......and maybe a little crazy............HELP !!!!! Dave

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Guest Seriousmojo

yup Ronnie.....that was it.........this a/c is driving me so crazy that I'm NOT seeing things lol......kinda tucked up in the right hand corner of the rad.......Think I'll just roll the windows up when the a/c works and roll em down when it don't Dave

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Not to screw you up, but this a.m. I swapped out my blower control module. I noticed that the A/C high presre switch lead wire was not snapped in place. Pulled it off and sprayed it with contact cleaner and reconnected the plug. It went on real hard so I forced it to connect and "lock" the clip fastener. This aft. took the car out for errand shopping and the A/C would not work, kept getting the low freon shutting off the compressor screen. Went over to my mechanic friend who has the yellow goggles and black light to verify no leaks. [There were none].

Went home disconnected the battery, reconnected, fired her up turned on the A/C and once again tripped the code. Disconnected the plug to the high pressure switch jumped the lead and A/C worked. Then took plug in hand bent the terminals inside the plug to make a better contact, reconnected plug and...

all is good! Works like it is supposed to.

Sometimes it is the easiest things that trip you up.

Just keep track of what you did.

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Guest Mc_Reatta

Condenser is full width right in front of the radiator. The coil is in front of them and is for the power steering fluid.

Is your AC set at max cool all the time or do you set it to a specific temperature? That is what tells the HVAC controller how to set the deflector.

Vacuum lines connected to it control which set of vents the air comes out of. Default is the defroster vents.

Hard to understand your problem if we don't know how you have the controls set and what is happening with the air flow into the cabin.

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Guest Seriousmojo

Ok heres an update.....and one of the downsides of getting old !!! Read Daves89's post and got to thinking about connectors......I had checked everyone except the one on the compressor.....YUP.........the wire on one side was frayed a little.......Had another plug like it so I spliced it in to check it...........guess what? you bet....that seems to have been the problem all along......I took it out for a spin around town (5 miles) and out on the interstate (11 miles) it's only 80 here right now,so I will take it out again tomorrow,,,,supposed to be around 95.......was blowin nice cold air the whole ride,,,had to turn it down.........Hey guys.....don't get old lol ............Dave

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People BD28 will tell all. Down around zero when running (goes to -5ish is low & will cycle), above 5 & higher the compressor is probably not compressing. Going up the comprressor is cycled off, coming down it cycled on. Can also usually feel when it cycles.

With older cars particularly it is important to listen to what it is telling you.

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Guest Seriousmojo

Took the car on a 200 mile round trip today.....average temp 94 degrees....... a/c wasn't ice cold but was more than comfortable.........sometimes it's the simplest things,and we tend to overlook em......Have a great day......Dave

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