Air Conditioner Problems (mcc) 1991 740

Prostar190 · Post by **Prostar190** » 19 Mar 2008, 19:32

Here is a problem I have been having with my 1991 740. When turning on the AC the compressor was not engaging. I tried jumping the plug at the evaporator with no success. I removed the MCC and cleaned all the connections and reinstalled. The AC worked great. It is intermittent not turning on the compressor, so here is my question, can someone give me detailed instructions on the MCC soldering fix? Thanks

190000 miles[/img]

Prostar190 · Post by **Prostar190** » 20 Mar 2008, 08:37

MCC = Manual Climate Control

Post by **billofdurham** » 20 Mar 2008, 13:50

Welcome to Matthew's Volvo Site.

can someone give me detailed instructions on the MCC soldering fix?

I am not sure to what this refers.

Bill.

Prostar190 · Post by **Prostar190** » 20 Mar 2008, 17:02

On manual climate control, the power comes directly from the control unit to the pressure switch. If there's no power at the pressure switch, then the problem likely resides in the control unit itself (dash control assembly with temperature controls and AC buttons). It is almost always bad solder joints on the circuit board (inside the tin box attached, in behind the front panel). The compressor relay is an integral component of the circuit board on this model and usually isn't the problem, but the solder joints are. The joints from the connector to the board, or board to the relay's pins seem to degrade with heat and time, and lose continuity. I would like to know if any body has attempted this fix and can shed a little more light on the procedure. Maybe a schematics or a pic. Thanks.

Post by **billofdurham** » 22 Mar 2008, 13:22

This is one I have not heard of but others may be able to help.

Bill.

Prostar190 · Post by **Prostar190** » 15 May 2008, 07:19

Hello,

Sorry for the late response for this fix. I have found a great link for the fix it works well and I have been freezing ever sine.

http://www.volvoforums.com/m_103107/tm.htm

Post by **billofdurham** » 15 May 2008, 11:47

Thank you for the update.

I have added this to the Repair Database.

Bill.