A/C Question

[jjc-hi]

Trying to get my a/c working (again), car is 1990 325is. When I bought the car the a/c wasn't working. Recently got a working used compressor from a donor car and had it installed on my car after converting the system over to R134. Had the dryer changed at the same time. It worked fine for about 2 weeks and then stopped blowing cold air. Mechanic checked everything and its holding the charge. Read related posts here and followed advice to also change a/c pressure switch, but still doesn't work.

Mechanic thinks the compressor went bad and suggest getting new one. Best price seems to be around $460 for a rebuilt one. Any advice on what else to check or is it likely I need a new compressor?

[416stroker]

. first does the pump run?

If so you didnt change the expansion valve did you ? Id get on that.

[jjc-hi]

". first does the pump run?"

Sorry, don't understand this question. Is the pump the compressor? No we didn't change the expansion valve.

[416stroker]

". first does the pump run?"

Sorry, don't understand this question. Is the pump the compressor? No we didn't change the expansion valve.

YES compressor/pump whatever.Well?

[Huff]

He may be right.. The compressor or expansion valve going bad will cause that. The system has enough charge, just can't produce the pressure. $460 is a good price actually. I sent my compressor off to re-built and that was $280.

I'm happy with there work: Polar Bear

[416stroker]

yes expansion valves get all gummed up. Then you dont get any cool air..

[Ryann]

As 416stroker said, the first thing you need to verify is that your compressor clutch is engaging while the engine is running and the a/c is switched on. <In case you aren't familiar with what an engaged clutch looks like, as you view the compressor with the system on both the pulley and the center portion of the clutch including the bolt that holds it onto the compressor should be spinning.>

Tell us what you see.

[jjc-hi]

416stocker and Ryann thanks for the responses. I checked the the compressor and clutch. When the car is off the clutch and bolt spins freely. With the car on and a/c off the clutch and bolt do not move. With a/c on the clutch and bolt still do not move. Bad clutch?

Seems like it is just as easy/cheap to replace compressor and clutch as it is to find/buy new clutch.

[redsubdivisions]

Funny that I'm reading this. If you want to go all out, flush out your lines, get new o-rings, a new expansion valve, a compressor, and obviously a drier. Then you will have a fresh system. I did this in a weekend while taking my time. I will let you know that the expansion valve is a giant pain in the asshole and I hope you have some free time to do it. Everything else isn't half bad.

[Ryann]

With a/c on the clutch and bolt still do not move. Bad clutch?

Possibly, but bear with me.

Now you need to verify that there is 12 volts present at the clutch wire when the car is running and the a/c is on.

[xwill112x]

Possibly, but bear with me.

Now you need to verify that there is 12 volts present at the clutch wire when the car is running and the a/c is on.

thisss.

start with the easy stuff to rule out.

[jjc-hi]

Possibly, but bear with me.

Now you need to verify that there is 12 volts present at the clutch wire when the car is running and the a/c is on.

OK, I need to figure out how to use the old Triplett voltmeter I found downstairs. Do I check at the main wire going to the compressor or do I need to check a specific wire on the the compressor.

[TurboJake]

Check any of the wires going to it.
There's only one.

[416stroker]

Funny that I'm reading this. If you want to go all out, flush out your lines, get new o-rings, a new expansion valve, a compressor, and obviously a drier. Then you will have a fresh system. I did this in a weekend while taking my time. I will let you know that the expansion valve is a giant pain in the asshole and I hope you have some free time to do it. Everything else isn't half bad.

Its not that bad you could change everything in a few hours. I just did my car today vacuumed it all and charged it in an hour or two.

The trick with the expansion valve it to use stubby wrenches

[jjc-hi]

Tested the wire with a/c running it has 12 volts. It was originally connected with a plastic connector, but it was falling apart so I removed it and covered the connection with electrical tape. Original connecter was for 3 wires but there was only the one wire going to the compressor.