hwyrnr

I would install the new heater valve and hook up everything back the way it should be. I would then make sure the heater valve is opening and closing as it should. Like I said in my previous post I had the micro switch on the temp slider go out. Not allowing the heater valve to close. this switch may also be connected to close the heater door valve.

This is just a possible guess. But even though your not circulating water. You are circulating the warm air from beneath the dash "heat from engine". You may be mixing the A/C air with warm air and not getting the cold air your expecting. Or that little micro switch triggers something else along with the heater valve to let the cold air from the A/C come into the cabin. I'm just making a SWAG.

When My 84 would not blow cold even with the A/C on I traced it to that failed micro switch. After I installed it I got cold air with the A/C on.

After I pulled the HVAC head unit out of the center console and removed the case from the unit I was able to check continuity of the micro switch pretty easily. and replacing it was easy as well. It just slides out and two wire to solder.

If your HVAC vacuum lines are in working order. And everything else is checking out, you may want to check the head unit.

Just my thoughts,
James

Deesta

Update:
Went for a 30 minute drive today and was cool for a bit then warm air with occasional cool air. I checked the air con pipe in the engine bay and instead of being very cold it was warm. I also noted that the condenser fan was not coming on at all. Am I correct in thinking that this could be contributing to the issue as the condenser would be getting very hot and therefore there would be too much heat to dissipate for the A/C to work efficiently? I understand that the 86.5 fan only comes on when it is very hot whereas the 87 on wards fans came on when the A/C was turned on. So I thought rather than troubleshoot why it won't come on I would install a relay so that the fan would come in when the compressor is engaged. Anyone done this and if so can you offer any advice. Thanks again for all the advice so far.

bureau13

I think that may be a worthwhile mod in the future, but for now, IMO, you need to figure out why it's not working as it should.

The aux fan can be triggered a couple different ways...to first make sure the fan itself is working, short the wires from the radiator temperature switch in the lower right front of the radiator (viewed from the front). The fan should turn on.

Deesta

Sorry, forgot to mention, I hooked up power directly to the fan and it worked fine. Must be a relay?

bureau13

There's a switch in the radiator as I mentioned, but more relevant here is the switch...I think it's on or near the receiver/drier? That's the one that should trigger the fan for AC purposes.

Deesta

I can't find the switch, however I have an update. I took it back to teh guy that fitted the new compressor etc. Funny enough it all worked perfectly. As soon as I drove out of the driveway it blew warm again. However I have since discovered that the compressor was only engaging intermittently. Thanks to further research on Rennlist I traced the fault back to the relay in the HVAC (head unit). I replaced the relay with one that was suggested and tested it yesterday and it worked! I haven't taken it for a good run yet and I am yet to see if the condenser fan cut's in however I have my fingers crossed that after about 15 hours of messing around the problem is now resolved. I will post an update once I have taken it for a good run.