ac compressor

[Guest Squire Tom]

hi reatta lovers

91 r12 ac has been working fine.

turned on today and no cold air no compressor turning.

switching between modes seems to work but no compressor on ac

temp was 80 outside and set at 65 inside .no workee

used search for air conditioning and did not see my issue n the last year.

where's a good place to start ?

thanx

[DAVES89]

First thing I do when A/C stops working is clear the codes. It has always then come back on after that. I do not know how to clear codes on a 90/91

[Guest Squire Tom]

will give it a try - there was no service ac light though

thanx

[Roadster90]

Disconnect power from the battery so the computer will re set...worked on my 90 when I bought it in 2002. Hasn't acted up since.

[Guest tomt]

re-setting codes and disconnecting the battery also worked for me. But don't forget the most important thing!!!

A shot of Jack Daniels before you turn the key. Worked for me.

[Guest Squire Tom]

hi again

disconnected battery for awhile and reconnected

no compressor

reset codes via hvac controls several times

no compressor

no bcm codes listed before resetting

bcm data was within ranges specified

cooling fan running

interior fans on auto - high

is there a code for low refrigerant ?

next step ? - local a/c guy ???

[Guest Squire Tom]

is there a fuse on the compressor clutch ?

is there a schematic of the two fuse boxes , as to what the fuses control ?

[D-a-n-i-e-l]

Did you check for voltage at the compressor clutch conection? If it is like th 88-89 then there is not a schematic of just the fuse block. For the most part, the fuses are found in the electrical trouble shooting section of the service manual. In there given system chart. Also, unless they went backwards on there sensors there should be a low "pressure" code.

[Guest Squire Tom]

no bcm codes or ec codes present

all das blinkin lites seem ok

ac controller seems ok

connection to compressor seems ok

am going to check all fuses

[Guest Squire Tom]

okey dokey

driver side fuse panel

20 amp

# 18 compressor now cycles on and off just like the general intended. hope it doesnt blow again

[Guest Squire Tom]

second time fuse has blown - wheres a good place to start ?

seems like it may have something to do with switching to heat mode / or maybe not

fuse blows - no compressor clutch

replace fuse clutch works for some time then it blew again

[D-a-n-i-e-l]

I would start with the clutch for the compressor. It is what that fuse is powering, if I remember right. The bad news is if that is the case, yo will most likely be replacing the pump/compressor. I hope for you I am wrong about the circuit.

[Ronnie]

See if a slow blow fuse is available that will fit. They handle a surge better when the compressor clutch first engages. Might cure your problem if you can find one..

[D-a-n-i-e-l]

That is a great idea, but I would still plan on replacing/repairing the compressor in the future. The electrical components were designed to run on a normal single blow element, so what ever the cause it will continue to decline until it is completely gone. I really do think that the slo blow is a good short term fix.

When does it blow? at start up of the compessor or after the compressor has been running?

[Guest simplyconnected]

Check A/C clutch coil resistance. If it's zero, you will need a new clutch. Blowing a 20a fuse means power draw, is exceeding 240 watts.

Got a continuity light? The cheap 2-penlight battery kind works well (Ideal makes one, or make your own). While you have the clutch disconnected, attach one lead to a clutch connector stab, and quickly wipe the other lead across the other stab. (On a 1-wire connector, use ground for one lead.)

You should see a pretty blue spark following your wipe wire, and the bulb should not light. This shows inductance. Try it several times. If you get the sparks, everything is good, and your problem is somewhere else. If you get a strong light with no spark trail, it's shorted.

Do this at dusk, or in a dimly lit garage.

An engine compartment is a hostile enviroment with lots of vibration, oil, heat, cold, etc. If the compressor checks out, follow the wire loom back, checking all along its length for fraying copper wire. If you find a bad spot, use friction tape, not black plastic electrical tape. Friction tape is cotton and will take heat far better than vinyl. We are not looking for a high-voltage dialectric, just a soft, hearty, insulator.

[Guest Squire Tom]

thanks for the suggestions - fuse does not blow right away. the last time it cycled for several days then i used the heater . next time for the ac - blown fuse.

when i first got the car it ran well for several months then started with the problem.

i was going to do the conversion anyway , maybe nows the time,but not till i follow the suggestions. maybe a wiring thing as suggested.

i wonder how much all the help i have received from the forum would have cost at the local Buick garage ?

thanx again

[Guest simplyconnected]

Just send all proceeds to me.

Compressor coils don't heal themselves. It's probably ok. Seriously check for wires rubbing on metal, especially on/around the engine, and passing through firewall holes.

Sometimes connectors get water and turn pins green, but that usually stops things from working and doesn't blow fuses. Again, start at the compressor and work toward the I.P. 'Intermittent' usually goes along with 'vibrations' or 'loose connection.' Rapidly turning your compressor on/off several times will blow a fuse (caused by loose connection).

[D-a-n-i-e-l]

a coil will act/be bad when hot, and when cold build enough resitance to operate decently. You need to check the coil when hot and cool if there is a large diffrence in resistance say more than 50% then it is most likely bad.

[Guest Squire Tom]

go figure - it has not blown a fuse since the last post - i have not used the heat setting since the last post.

compressor wiring is buried in the 91 and i need a lift to get at the wiring.

where does the compressor leads ( two wires ) show up in the cockpit or firewall ?

[D-a-n-i-e-l]

You should be able to get to the wires by removing the passenger side tire and a jack. If you want to find them in the engine compartment I would look at the electrical trouble shooting manual to ID the wire color and then find them at the fire wall conection.

[Richard S]

Some posts suggest the 90 will clear codes if the batt is disconnected for while. Another says disconnect AND clear codes. Is there another procedure for clearing the 90 codes besides disconnecting the batt?

[padgett]

Disconnecting the battery for around 30 seconds will clear the codes - they are stored in volatile memory. There is also a way to jumper from AFAIR the low pressure switch and power the compressor clutch directly.

Finally, the clutch can be replaced without opening the system but you will need a pulling tool (about $40 from NAPA).

[Guest Squire Tom]

thanx daniel for the tip

there is a relay in the drivers side front for the clutch , the fuse has not blown again and the ac is working ok

clutch connections seems ok

still have to see if using the heater control had anything to do with it. this is all i can remember doing differently .

i have have left it in auto and medium fan and so far is still working.

[Guest Squire Tom]

go figure , the fuse is still intact , with little done by me.

ac works well on auto setting - have not tried to use the heat ,that seems to be a thread in the fuse issue. one odd thing though , once the fan was on high in auto and then dropped down a little in speed and the fan control would not increase or decrease the speed. the next time i started the car the fan on auto worked just fine.

just some observations for those more knowledgable than i

[Richard S]

My a/c was working and now does not. The dash has the "service a/c" light when I turn on the a/c. My problem is that the car tells me that the refrigerant level is low, which I think will not let the compressor come on. But how do I know if the problem is the compressor in the first place, or just the refrigerant level? I suppose the answer is to re-charge the system and then see what happens, but I was wondering if there is way to test the compressor independently to make sure it will come on. Would hate to recharge and then have to replace the compressor afterwards.

[Ronnie]

Have you tried reseting the codes by removing the battery cable? Sometimes your problem will go away.

If you have done that you can unplug the connector from the low pressure switch and insert a jumper to bypass the switch. See photo for location.

Turn the A/C control to the lowest setting. The compressor clutch should engage. I would not let it run long as it could damage the compressor. If the compressor runs you need freon or have a bad pressure switch.

If the compressor doesn't run you have another problem with the compressor such as relays, bad clutch etc.

[Richard S]

Ronnie, I had the battery out for a while while I upgraded the brakes. It was after that the compressor elected not to come on. Also, I just replaced the battery, I doubt that is the issue. I will try jumping the switch to see if that motivates the compressor. Ronnie, will removing the switch allow the freon to escape? If so, replacement of the switch will have to be done by an a/c shop.

[Ronnie]

It would not hurt to try resetting the codes again by unhooking the negative battery cable.

There is s Schrader type of valve that the switch screws into. If the valve is working correctly not much freon should escape.

[DAVES89]

I too have a low freon warning. As a matter of fact it turned off the compressor. According to my mechanic friend he diagnosed that my condensor is leaking. I have to replace mine. Fortunatly I have been buying freon[r-12]as well as a condensor,washers and a/c oil.

[Ronnie]

Dave,

If you ever contemplated changing to 134A, while you have the system down to replace the condenser, would be the time to do it. There shouldn't be much additional cost involved to change to 134A while you have the condenser off. If you have to add freon in the future the price difference between the R-12 and 134A would certainly offset the extra cost of changing over to 134A.

[DAVES89]

I've thought of that, but I am sitting on 10 cans of r-12 freon and have the r-12 refill kit/hose.

[Guest TommyH]

Wow! Ten cans! Doesn't it only take 2 to recharge a system?

[DAVES89]

It takes 3-12 oz cans to fill an evacuated system. I have been buying freon in EBAYs buy it now. I have not paid more then $25.00 per can and some of them included freight. Certainly it is more expensive now.

[Richard S]

I ran the jumper test that Ronnie suggested, and the compressor came on. I am assuming low R-12, and since the PO said he had done this a while back, I am also assuming a slow leak. In anticipation, I bought leak sealer, oil, and R-12. Obvioiusly the leak sealer would go in first. Would it be adviseable to put the R-12 or oil in next?

[Ronnie]

If the compressor comes on a puts out cool air I would wait for the sealer to do it's job before adding more freon. The compressor must be running in order for the sealer to stop the leak.

As a side note, I have never had any luck with the A/C stop leak. Good Luck! Maybe it will work for you. I prefer the red dye that can be added to the system to show leaks around fittings etc. When you find the leak with the dye you can fix the leak the right way instead of relying on the stop leak to temporarily stop the leak

The best way to find a leak is a leak detector device that is commonly called a sniffer. It is a highly sensitive device that detects the freon coming out of a fitting or pinhole and sets off an alarm. Any professional A/C technician will have a sniffer.

[padgett]

I have heard that too much "stop leak" can clog the oriface tube - no more than one can's worth if you must. Any time I have had to open an R-12 system, I change to 134 and that includes full flush, vacuum check, oil, orifice tube for 134 (I general pop the $5 extra for a variable or "police" unit - seems to help at idle), and accumulator. New O-rings (green) for any opened fittings. Cheap insurance.

[Richard S]

The only reason I opted for the stop leak is that the leak is VERY slow, and I have the R-12 on hand. If and when things get bad, I will do as Padgett suggests. Thanks for making the point that I have to run the system with the stop leak for a while to allow it to seal. In looking at a few "recharge" websites they all agree that the oil goes in BEFORE the freon. However one site says to start by "vaccuming" the system. I have an old compressor run a/c vaccuum, but wonder whether it is necessary for this job. Is this a form of leak test? Would it remove all the old freon? Would it remove moisture from the system?

[DAVES89]

When I changed my condensor this spring, I took my car to my mechanic friends dealership where he works. I was charged $51.00 to have my system evacuated. I then went home and added the dye, oil, and freon. I thought the money was well spent.

[Ronnie]

It sounds like you are mixing two separate and distinct procedures.

1. <span style="font-weight: bold">Topping off a system that is low on freon due to a small leak where the A/C just stops putting out cold air.</span> In this case the system has not been opened and has not completely lost it's charge (no air has entered the system). This procedure only requires finding and fixing the leak if possible without opening the system and losing freon (such as tightening a loose fitting). Then adding the proper amount of freon to return the A/C system to operating condition. Normally no oil is needed and evacuating the system (vacuuming) is not necessary. This can usually be done by a shade tree mechanic with a can or two of freon and a hose kit.

2. <span style="font-weight: bold">Repairing a system (replacing parts) or changing it over to 134a where the system must be opened and the freon removed or lost to atmosphere.</span> In this case the system should be flushed, at the least a new filter/dryer should be installed as well as new o-rings. The system should be fully evacuated. A leak down test should be performed at this time to determine leaks in the system. Then new oil should be added as well as the proper amount of freon. This procedure should be left to the pros. You need a lot of special tools to disconnect lines and hoses, to pull the clutch off a compressor as well as proper equipment to evacuate the system. A good set of A/C gages is a must when doing this type of work. A can with a hose attached just won't get it.

[Richard S]

You are generally correct Ronnie. Confusion is my natural state of mind. Will do as you suggest and try the stop leak and the recharge. If that fails, then go the conversion route.