AC not working

[PopsRide]

The AC doesn't work on my 98. The refrigerant is charged, I hear the relay click when I select AC, all fuses look good. But I don't hear the compressor kick in, don't feel any extra load on the engine and don't get any cool air. Has anybody run into this before? If it's a simple fix, I may be able to do it myself, otherwise I'll put it off until Spring.

[spinne1]

1. How do you know the refrigerant is charged?
2. Does the compressor clutch turn on (you can watch it while the car is running with the AC turned on)?

You need to get some gauges and hook them up and see what the pressures are and then go to the forums at ackits.com and post your pressures and problem there and you will get good advice.

[Bassasasin]

The clutch wont click unless the clutch is trying to engage the system wont try to engage the clutch (click) unless theres sufficient gas. Apparently the clutch isnt engaging but is getting the signal.

.. For now I suspect the clutch


Good luck.

[PopsRide]

I put a gauge on the AC system and it indicated that that it was fully charged. How can I check if the compressor clutch is engaging?

[Bassasasin]

I would expect that you could hear the pump clutch engage and disengage providing there isnt too much engine noise already.

Unfortunately the compressor is way down there. But there are wierd things you can do like listening to the handle end of a very long screwdriver touching the pump but you have to be careful.

When it engages the motor may very slightly slow a bit but the system usually has a compensation for that from the computer soz not to feel it while driving unless you are feeling very closely.
You could feel the pipes too for hot and cold pipes. The large pipe comming from the firewall is the low side and should be sweaty and not frosty.

Example: Engine running I start adding freon. The clutch starts clicking and then gets to where it clicks on solid then I like to hear it at about 50% on/off cycle. This gives me a approximation when adding 134A to a low system. As I understand it there is a low pressure cutoff and a high pressure cut off. The clutch engages and runs pressure up to the high cutoff point and waits for the gas to bleed down as it is expanded in the evaporator.

Anyway if you determine it is the clutch I think the whole pump has to be removed. This includes draining the system, removing the pump & clutch and replacing it and reverse the process. Hopefully its not something like the pump has frozen up previously and burned out the clutch. This may be a drastic situation for the AC. Some call it the Black Death and the cost of repair is so high to clean replace revive it is so great that they sell the car.

PUT OFF TILL SPRING?? Your defroster uses the AC to dry the air.. expect foggy windows.

But, Im no expert. Just a forum regular.

[HotZ28]

Originally Posted by PopsRide

I put a gauge on the AC system and it indicated that that it was fully charged. How can I check if the compressor clutch is engaging?

With the above statement, I guess I am getting confused! How did you check the refrigerant charge without the compressor running? In addition, the 1998 should have a V5 compressor, which uses a variable stroke compressor to control the system pressure, rather than pressure switches!

You need to get the compressor running to check the high & low side to see what you really have. I would suggest that you have the system evacuated and see how much refrigerant is really in there. After you evacuate and hold a vacuum for 30 min, you should be able to charge it up enough (using system vacuum) for the compressor to engage, and then fill it to specification.

If after you get the refrigerant charge correct and the compressor clutch still does not want to engage, I would then look for other electrical or mechanical problems. I.e. clutch - orifice tube etc.

[spinne1]

Originally Posted by PopsRide

I put a gauge on the AC system and it indicated that that it was fully charged. How can I check if the compressor clutch is engaging?

You physically look at the compressor. If the clutch is engaging, you will see the front part of the compressor spinning. If not, it will be sitting still.

[PopsRide]

I bought one of the DIY AC charge kits that came with a gauge. When I attempted to add refrigerant, the gauge showed the system as fully charged. Do you think that this may have given me a false reading?

I don't know much about the compressor, but when I press the AC button, I can hear a relay (outside firewall in engine bay) clicking. I don't hear any specific noise from the compressor due to the engine noise.

[Bassasasin]

Sounds like its trying to turn on the clutch there... Maybe you can somehow carefully probe test light to the compressor clutch actuator control line near the clutch and see if it gets voltage when you hear that click.. It may be that clicking relay is bad on its output or that circuit to the clutch.

I looked at mine(94') for you, it may be totally different but, on mine the clutch connector is bundled into a larger bundle cable about 10 inches from the connector and appears to be routed across the front of the motor and then back somewhere, proubbly back to a similar high current relay as yours. I would suppose the connector at the clutch could be disconnected and you temporarily could look there for voltage. Mine has two wires at the connector and one side is ground. Its pretty tight down there. Have to be careful.

Good luck

[PopsRide]

I removed the connector on the compressor and attached voltmeter probes to it. When I cycled the AC switch on and off, it indicated that there is no power going to the unit, so the problem is not likely to be the compressor. Hopefully it is something much less expensive!

I think that the "clicking" sound I was hearing is an actuator moving, not a relay! Has anybody run into this before? Is there a relay that I can check, or a fuse (all fuses in the fusebox are OK) that might be the true problem?

[Bassasasin]

What about the relays?

Bass

[HotZ28]

On a fully charged R-134 system such as yours, you should have 70-90 psig on the low side, without the compressor running. That would simply be residual system pressure. If you were low on refrigerant, the low side would measure less than that and would be deceiving when trying to get a reading. It might be low enough on the gage to indicate that it is fully charged! (30-50 psig). Try adding some refrigerant to see if it will take a charge and engage the compressor. Like previously stated, you cannot get a true reading on the gage without the compressor running! The system is designed to not engage the compressor, without a minimum refrigerant charge!