TeamCapri

General => General => Topic started by: greywolf27030 on September 01, 2018, 10:25:15 AM

Title: PCM to get my A/C working
Post by: greywolf27030 on September 01, 2018, 10:25:15 AM

It appears I have a PCM problem.  My A/C compressor won't turn on.  When you ground the white A/C relay wire(PCM wire), it comes on fine and blows cold.  I'm guessing a PCM problem.  The cruise control also quit working.  Maybe also a PCM problem.  Does anyone have any experience with this?  The car is a 91 XR2.  Does anyone have a spare XR2 PCM?

Jack Byrd

Title: Re: PCM to get my A/C working
Post by: Rocketman on September 03, 2018, 07:09:43 PM

I don't think the PCM controls these items. Particularly the cruise control. It has its own module under the dash

Title: Re: PCM to get my A/C working
Post by: blueamber on September 04, 2018, 12:20:06 AM

That white wire is from the PCM to turn on or off the AC clutch if a bad pressure condition is sensed by the AC clutch cycling pressure switch.  If the pressure is too high you've got something wrong in the system that must be fixed, too much freon, clogged evap, something... If the pressure checks out OK (not too high, not too low) then maybe bad is the PCM, wiring, pressure switch, AC module, could be lots of things.

Title: Re: PCM to get my A/C working
Post by: greywolf27030 on September 04, 2018, 10:01:34 AM

Pressure is fine.  The only way the clutch will function is when you ground the white wire to the PCM.

Thanks, Jack Byrd

Title: Re: PCM to get my A/C working
Post by: greywolf27030 on September 04, 2018, 10:05:58 AM

Quote from: Rocketman on September 03, 2018, 07:09:43 PM

I don't think the PCM controls these items. Particularly the cruise control. It has its own module under the dash

So I"ve got two problems, crap.

Thanks....lol

Title: Re: PCM to get my A/C working
Post by: greywolf27030 on September 04, 2018, 05:53:14 PM

I interpret the schematic as the A/C relay is activated by the white wire that goes to the PCM.  This is reinforced by the fact that the compressor operates when you ground that white wire.

Jack Byrd

Title: Re: PCM to get my A/C working
Post by: belleaudb on September 04, 2018, 08:38:33 PM

The PCM will disengage the a/c compressor at full throttle.  Is your throttle position sensor working properly?

Title: Re: PCM to get my A/C working
Post by: greywolf27030 on September 05, 2018, 09:42:04 AM

Haven't experienced any drivablity problems.

Thank, Jack Byrd

Title: Re: PCM to get my A/C working
Post by: Rocketman on September 07, 2018, 12:25:27 AM

Can you check continuity on the pressure switch to see if the switch is seeing proper pressure?

None of my Capris have ever had working ac, I removed most of it, so I'm not terribly familiar with it.
If you want I gave give the schematics a dive and see what that to expect on that wire

Title: Re: PCM to get my A/C working
Post by: greywolf27030 on September 07, 2018, 05:54:18 PM

Thanks, I found the manual on the A/C and the first step seems to be check for power on the white wire at the PCM.  I'm trying to arrange to get the manual printed so I can start troubleshooting.

Jack Byrd