87 xj6 Heater and AC were working perfectly. This morning, turned hater on and all it blew was AC. Same on every setting even defrost. Blowing out center vent too very cold. Engages condenser too. I tried to research several articles and have checked the vacuum and function of the heater valve - ok and actuator on drivers side console side panel - ok. Passenger side mechanisms do nothing. I disconnected the amplifier to see if that changed anything. Did nothing. Same condition all blowers in and AC ice cold. Will continue to scour through the great articles, but if anyone has another test or suggestion while I do it is greatly appreciated. Thanks!

 

First, when you turn the temperature dial to a different setting do you hear a faint whirring from behind the dash? You should. It indicates the system understands your request for a temp change and is trying to comply. If not, we'll have to find out why

Cheers
DD

 

I know exactly what you are referring to, and I dont hear it (and truthfully it’s hard to because both blowers are on and ac is loud. The only thing that makes a sound is the ac compressor and drivers side vacuum mechanism that moves the flaps.

 

place rhe switch in LOW so you can't hear the blowers but you can hear the Servo.

 

Check the heater valve on the fire wall in the engine bay. And the vacuum reservoir, over by the brake cylinder. Plus the vacuum hoes that abound there. Including the ones under the battery tray that go from the engine bay to the cabin. Can't see those, only feeelif they are present and connected..

Carl

 

This must be the first time ever someone has too much air conditioning. Usually it is no A/C.

 

UPDATE: Tonight I got the car to temp and switched between settings. For the first time since it had the issue, the servo did try to change settings and it did intermittently to heat out of side vents and foot, then fine out of blower. Then when I switched to cold temperatures, it switched over, center vent ice cold. But when I tried to go back to heat, it went back to full AC out of every flap and blower and no servo function. Several times to change again, and no luck. So, it seems something isn't working consistently, rather, intermittently and reverts to the all AC.

 

Update - intermittently. I did a few times tonight, then the servo stopped and went back to full AC. It did a few times, then nothing.

 

It is either the servo or the amplifer or both that are faulty. JagAire have all the bits you need, have clear test routines you can use that pinpoint the problem and are very helpful. There is a potentiometer on the servo that responds to the amp, and eventually it's tracks wear unevenly and the servo itself functions erratically. It sounds like this is what is happening.

 

Fixed! It was indeed the AC Amplifier and our friends at JagAire saved the day! They are very, very helpful and considerate about selling you the right part only if you need it. In my case - it was the perfect solution! Thanks all for your help! Great forum!