What the? The A/C and fan work sometimes but not always?

[sorny]

What the? Car overheats and fan usually doesn't work when the AC is on

I just bought a 94 GT yesterday. Drove it for about 5-6 hours because I had to do some traveling. Shouldn't have taken a car I didn't quite trust yet but it's pretty nice and during the test drive it was fine so I headed out. After driving all that time (98% highway) I never had any problems.... air was ice cold the entire time and it never overheated. Then I get in some slow moving traffic and in no time it's overheating (in the red almost on the stock gauge) and today the AC starts acting up.

When the switch for the AC is on AC or MAX either one sometimes it kicks on and it's ice cold (and you can hear the ac clutch "click") but then while its running I can hear the ac clutch disengage and the air from the vents goes back to outside air temp. I also notice that the fan, which WAS running while the AC was on MAX is now off and the car starts to overheat unless I'm cruising at higher speeds.

I'm not sure what to think about it except that I'm really disappointed that the car I've owned 1 day is already overheating and the AC has already messed up. Are these two things related? I searched the forums for a little while about the fan problem and read about the CCRM and all that but don't think what to think about it, I'm kind of overwhelmed with info about a car I just bought. I thought I read though that the CCRM controlled the AC and the Fan so I thought maybe it was dead but I dunno if it makes the AC clutch kick on and off or not.

HELP PLEASE! I hate buying a car that's new (to me) and having problems right off the bad

EDIT: I forgot to mention that when troubleshooting the CCRM I grounded pin 17 to see if the fan would kick on and it did NOT. I thought well if doing that makes it run the fan on high with a switch I can do that until I get this figured out but I grounded it to 10 different grounds just to make sure and it never kicked the fan on either. I unplugged the ECT and the fan didn't kick on so I jumped the pins on the ECT's plug and the fan never kicked on either. At no time have I ever heard the high speed fan kick on and only a couple of times have I seen the low speed fan on but its just at random times. The AC can be on and the low speed fan may or may not be on.... Also, I ran a KOEO test and I heard the fan is supposed to kick on when you do the test but it never made a sound.

I normally don't have any problems working on my own cars but wow I'm overwhelmed here. It's like it could be the fan, fuses, wiring, CCRM, temp sensor, ECU, what else?

 

[sorny]

Well I went out and checked the car again after reading another post about how the car will shut off the AC when it overheats to keep it from overheating even worse. So maybe that's why the AC quit working -- and it makes sense, the AC always switched off when it was getting hot, not when I first started the car.

Ok, now I also read that the coolant temp sensor that's on the passenger side (near the thermostat) controls the CCRM and fan speed and NOT the temp gauge right? Well I read that if you can disconnect that temp sensor when the car is running and it should cause the fan to kick on. I unplugged it a minute ago and the fan didn't kick on. And the car has cooled off a little so I went out, started it, turned the AC on MAX and it was blowing nice cold AC but the fan wasn't working at all. Maybe it's just an overheating problem and not an AC problem at all.

If unplugging the ECT should cause the fan to kick on and it doesn't does that mean that it's a problem with the CCRM?

 

[HISSIN50]

You cannot jump the ECT pins. It's a thermistor.

Look for a circuit breaker on the fan connector. If you're breaker is opening, the fan will shut off. When the temps get up to the 240* neighborhood, the AC shuts off.

I would get the fan control issue figured out and see if the AC is fixed in the process.
You can do the CCRM diagnostics if you want. I would be prepared to just enable a stand-alone fan control circuit however. It can be easier than trying to fix the OEM circuit.

Good luck.

 

[HISSIN50]

How did you do that? Your second post was not there when I posted - I just got a notification for it (as if it was posted on Sunday at 5:23 PM).

Anyhow, When your AC is on but the fan is not, did you do the CCRM test for the high speed fan?

You're right about the ECT. It's for the puter and fan. The gauge has its own sender on the driver's side.

The ECT being disconnected but not having the fan come on can also be a wiring issue or an EEC issue.

Having no fan or the EDF only, with the AC on, can cause hot temps pretty quick.

Good luck.

 

[sorny]

Wow I posted the first stuff way too early and half of it was wrong. What was actually going on was, as you said, the AC was shutting off because of the overheating so it wasn't an AC problem at all. The fan would come one sometimes but not always. When I unplugged the ECT or grounded pin 17 of the CCRM it wouldn't come on. 90% of the time when I turned AC on MAX it'd come on but on low speed and the car would still slowly overheat. The oddest part was when I'd run my fan straight to the battery and when trying the + and - it wouldn't work most of the time but sometimes it would spin up. So on one of the times it wouldn't kick on I smacked it and it spun up.

So I knew it was the fan and bought the entire assembly at Advance Auto. It was $179 but they had a coupon for $30 off $100+. I could've just replaced the motor but it only took 10 minutes to take the old out and put in the new assembly entirely so I paid a little more to save time. Works great now I think. I thought it was almost running all the time now though but I realized was pretty warm today and I was just checking it while it was idling in the driveway after being hot so I guess of course its gonna run then. In the morning I'll be checking to make sure it doesn't come on first thing when I start it since the AC won't be on and it'll be cold. I'm thinking it'll work fine.

 

[HISSIN50]

Glad to hear that it sounds like you got it fixed.

Don't feel bad about not just swapping the fan motor. Half the time the fan blade won't divorce from the motor's output shaft so you need to get a new fan assembly anyhow.