[whitec1001]

Just got the Cruiser back up and running. After replacing the broken timing belt. ITS ALIVE. well sorta. I can drive it. The issue that I am having now is we pulled vacume after having to open the system to replace the belt. We recharged it and its full however the fan isnt coming on when the AC is on in the car. If you let the car sit and idle when it needs to cool the fan comes on and does it job. I have tried the paperclip test thing on the AC switch on the firewall. what else can I do to futher diagnose the problem at hand. if not ill be driving around with no AC.

 

[Bob Lincoln]

So the A/C compressor doesn't engage, either? But the cooling fan does turn on when the car gets warm? Are you sure that you plugged in all of the electrical connectors to the A/C? All cars since the 1970s have a power connector to the A/C clutch and a low-pressure cutoff switch. Most cars since about the mid-80s also have a high-pressure cutoff switch on the compressor. Make sure all three are plugged in.

How did you determine that the system is full of freon? What is the static pressure reading (engine off)?

Does this car actually require discharging the A/C to change a timing belt? On many cars, you simply unbolt the compressor from its bracket and swing it to one side, without opening the system.

 

[djsamuel]

Does this car actually require discharging the A/C to change a timing belt? On many cars, you simply unbolt the compressor from its bracket and swing it to one side, without opening the system.

The PT does require discharging the A/C. I've heard of some people moving the compressor, but I've done it three times, and think it is easier to just discharge it and get the plumbing out of the way.

If in fact the compressor is turning on, then I would check to see that the wiring to the fan was not damaged. The engine is moved quite a bit when changing the timing belt, and you never know if it got pinched somehow. But, Bob's points are right on. Make sure the compressor is turning on and the system is starting to cool.

 

[whitec1001]

The compressor is coming on. Infact if you turn the air on when driving down the raod with enough air to cool the coils or what ever moving air cools thru the radiator the air inside gets cold. its just the fan isnt coming on when you turn on the AC . If the engine needs the fan while idle or what ever it does come on and cool the engine.

 

[Bob Lincoln]

OK. Most Mopars from early 1980s on are wired with the A/C compressor relay cascaded with the fan relay. That means that the fan relay must close in order for power to get to the A/C relay. So there probably is a computer signal that is sent to turn the fan on, but it's being lost somewhere. I'm not as familiar with the newer cars (mid-90s and on), but instead of a fan relay, the vans and some other vehicles have a solid state relay (MOSFET) which is the switch to turn the fan on. And there is a temperature probe, I believe, in the condenser, that triggers the fan. So maybe that probe is unplugged or damaged? Someone here who has owned a PT should know.

 

[djsamuel]

I THINk there is an A/C fan relay. that's awful I'm not sure since I have one. But, you can open the box in the engine compartment that contains the relays and look at the labels and see if there is one for the A/C fan. Or, someone else here with a better memory (or a manual at their disposal), can take a look and verify whether or not there is one.

I'll try to take a look when I get home from work.

 

[whitec1001]

Is it possable that the low speed portion of the fan could be bad ? Im going to go get a low spped fan relay today. It is the only one in the fuse box so I dont have anything to swap it out with to test like the horn relay. its strange.

1) Fan does not come on at all when AC is turned on. But compresser does.
2) While driving with air moving have nice cold AC.
3) Fan does kick on to cool engine when needed.
4) All connections are made to AC unit and fan.

Any other ideas clues hints what not is greatly needed. its going to get hot in Florida soon.

 

[djsamuel]

Is it possable that the low speed portion of the fan could be bad ? Im going to go get a low spped fan relay today. It is the only one in the fuse box so I dont have anything to swap it out with to test like the horn relay. its strange.

1) Fan does not come on at all when AC is turned on. But compresser does.
2) While driving with air moving have nice cold AC.
3) Fan does kick on to cool engine when needed.
4) All connections are made to AC unit and fan.

Any other ideas clues hints what not is greatly needed. its going to get hot in Florida soon.

It is possible. That is what happened to my PT, although it was the high speed fan that went bad. I just tested the fan by applying 12 V to both the high and low speed fan connector pins and seeing if the fan would run.

 

[ImperialCrown]

The Low speed fan wire is Dk.Gn. The High speed fan wire is Yellow.
If you have the engine running and the A/C on and you have 12 volts to one of these wires with no fan running, you have a 2-speed fan motor issue and it will probably need replacement.

 

[lilhow]

my PT did the same high speed runs on A/C fan was defective. I got the car cheep because of blown engine hmmm wonder why. Machanic friend replaced motor left me to recharge A/C ( I am refrigeration tech ) thats when I found out about fan.