I've got a 92 model 740T, which has had ac problems since i've had the car (about a year). Took the car to the local garage, mechanic fairly knowledgable on Volvo's he charged the system and it worked ok for a couple of weeks. Then I get no light on the ac switch and the compressor will not engage. Back to the mechanic, checks everything and says the ac relay which is built in the controls is bad. I replaced the climate control unit with a good one, and basically the same thing, worked for a few weeks and then failed. The compressor did not sound very healthy, really bogged the car down and let out some awful screeches a time or two. Is the compressor faulty and if so is that what's causing the climate control units/relay to fail. Second question are the climate control units repairable and if so, who repairs them? Thanks in advance and please forgive the laymen's terms as I am not a mechanic.

 

Yes usually the compressor overheats the control module and makes it go bad.

Some are repairable. All they need a is solder job on the circuit board.

 

Is there someone out there who I could send these to and what does the repair usually cost, or would I be better off trying to find a used good one. Thanks

 

I do them at the repair shop I work at.
You should be able to find someone close that would be able to do it.

Most indipendant shops know how to do it.

They will usually charge 1 to 1.5 hours labor.

 

I live in somewhat of a small town and getting a mechanic to pull a Volvo in the garage sometimes is a chore, although I believe the 4cyl 740 is not an overly complicated creature. But anyway, thanks again and if I can't find anyone in this area I may get back with you on some advice about who would be willing to do this. Thanks

 

Are you somewhat handy?
If so I could post how to do it.

 

I might possibly be handy enough, if not i've got some friends who are "handier" than I am. I've also got two of the units so we could guinea pig on one, and if it didn't work or I messed something up, no big deal. If you want to post it that would be great. I am familiar with getting the climate control unit out of the car, but from there i'd need advice. Thanks again.

 

Ok give me a day or 2 and I will post it.
I have to get the spare module I have at work and bring it home. I already repaired it but can still show how to take it apart and what usually goes bad.

BTW it is a MCC unit right?

 

A day or two or whatever will be fine. I won't need the ac for another couple of months. You lost me on MMC? Here is alink to what the thing looks like. Got one more question why I got you here, what spark plugs and gap do you reccomend in this car. Once again, 92 model 740 Turbo. Thanks again.



[IMG]local://upfiles/9127/3B0362C4BA81415F89C2D5B112DDF131.jpg[/IMG]

[IMG]local://upfiles/9127/ABD97847AFAB4A64900E5EA718775D49.jpg[/IMG]

 

Yes that is MCC.
MCC= Manual Climate control (Colors for Temp settings)
ECC= Electronic Climate Control (Numbers for temp. settings also has AUT on the module)

 

Got one more question why I got you here, what spark plugs and gap do you reccomend in this car. Once again, 92 model 740 Turbo. Thanks again

 

Alot of people use Bosch Platinums gapped at .030 Thousands.

 

Hi
I have had a similar issue with the AC in my '91 740 turbo wagon. I removed the MCC and melted the solder joints in the pics, and a few others where wires connected the board. It didn't look like any were cracked or loose. I didn't think new solder would fit on the joint without making a mess. Put the MCC back in and it still doesn't work. The compressor has recently been replaced, and I am pretty sure I have pressure, and the pressure switch has been checked and is OK. Where do I go from here?