Oldtee

I noticed that at rush hour highway crawl that my AC is not as cold as one might expect. At 82F I get a temp of about 50F but at 60MPH at 82F I get a temp of 40F or a little lower. Measurement is taken at side vent on drivers left. AC is using R134 in an un converted R12 system. Normal? is it trying to tell me something?

Oldtee

Scheduled tomorrow to top off the AC with new juice. Will see how it does after that.

Alan

Well if you are running just about @ idle vs normal 3K+ RPM then your compressor may have a very hard time coping with a high heat load. it will still cool and more R134a may help - but it cannot be as effective at low speed as a high speed when it is working very hard. On merely warmish days it will probably be able to keep up and once the car is already fully cooled you won't notice it too easily anyway..

In Phoenix its quite obvious it can't keep up at idle when its 110 degrees outside... it still cools but not anything like enough till it gets good revs...
my system is capable of very chilly air when its running @ speed...

40F@ 82F isn't bad - but you may need a bit of work anyway... (82F is still merely warmish in my book...)

Alan

Oldtee

Youse answers R good. Thanks.

j.kenzie@sbcglobal.net

Check to see if your electric fan is coming on. It is normally controlled by a setpoint of high coolant temp or high refrigerant temp or pressure(can't remember). The refrigerant switch sometimes doesn't work. You can wire it to come on when ever the AC clutch comes on. This might be enough to drop your vent temps plus adequate R134 charge.

SharkSkin

Also, I'm not sure if the front electric fan is supposed to come on with the AC in your 85. If it doesn't, you can modify/fix it so it does. Airflow over the condensor is the key factor, the weak link in the chain in this case.

Oldtee

Update. Took 2 1/2 cans of R134a to get the temp down to 44F at 2500rpm and the fan in the #1 position.

And, the radiator electric fan does not come on. I checked the fuse, replaced the relay and then jumpered 12V directly to the fan and it ran. So, it looks like something in the thermostats or switches or wiring is causing the fan not to operate. Fixing it to come on with the AC is a good idea. I'd like suggestions on where and how to do this so I don't screw up something else in this electric moster.

docmirror

First you want the fan coming on as it's supposed to, with the AC when certain conditions are met. The Aux fan is on page 4 loc H33 of the wiring diagram. Start with the ground side and make sure it's connected. Next, follow the hot side from the aux motor, back through the harness and locate the "pre-resistance aux fan"(good luck). Test it for continuity, and chase that back through pin 13 of the 14 pin connector to the "Thermoswitch intake pipe"(good luck again). This leads back to a +12V supply from the 30 buss in the central electric via pin 12 of the 14 pin connector and a separate wire bundle. What this means, is that whenever the key is on, one side of that "Thermoswitch intake pipe" should have 12V all the time. The aux fan is switched by thi "Thermoswitch" which is in the intake pipe.

Jumpering it to run when the AC is on is possible. There are several ways to go. My opinion is that you only want the aux fan to run when the fluid is circultaing in the freon lines and passing through the condenser in front of the rad. If so, locate the pick wire that goes to the AC compressor clutch. This is switched 12V on when the coolant is flowing(that's what the clutch does). Get some 16Ga wire, an inline 20 amp fuse, and a simple 12V auto relay. Mount the relay anywhere to a metal part of the car. Splice into the wire to the AC clutch and connect this to the coil of the relay, pin 86. If there are 4 pins connect pin 85 to ground. Find a suitable 12V source, typically from the 30 Buss, and splice into that using the in-line fuse and wire. Connect this 12V source to pin 30 of the relay. Connect pin 87 of the relay to the non-ground lead of the aux fan.

Now, when the AC clutch is turned on by the AC control circuit, the 12V will also pick the relay, and supply 12V from the 30 buss to the aux fan causing it to run. When the clutch line is turned off, the relay will release and the aux fan will stop. You shold know that the relay in the AC head which turns on the clutch is underpowered, and will likely fail once this is installed. Another way to do this is to use the AC button to switch the aux fan on. If you do this, the aux fan will run anytime the AC button is pressed in.

Get it working as specified, and you won't need a bypass is my opinion.

Doc

Bill Ball

2 1/2 cans is essentiually a full charge. You have a leak.

Oldtee

Leak? No doubt a biggie. Other strange things with the fan. It started to work but I need time to see if it works in the correct sequence. It ran with the AC on but the engine cold which I think, from the schematic, is not correct. I need to retest this situation. Just another electrical gremlin to chase down when I get back from SITM to go with the seat which won't go forward or the speedometer that only works when it wants, not when I want it too.