Overheating w/ AC : Details Inside

1995 Dodge Intrepid ES -

It's overheating only when the AC is on. Turning the AC off quickly reduces the temp. This started Friday. It runs fine highway or surface, stop/go or cruising. ONLY when the AC comes on is there a problem.

Normal Causes of Overheating:
I don't believe it is the fans: The fan motors were replaced approximatly 2 weeks ago. The Driver side (single speed, I believe) fan is working fine. I haven't HEARD the passenger side fan, however after "setting" it and marking it, it is moved - so I can only assume it's working as well.

It is not a coolant level issue, as that's been checked, double checked and triple checked.

It is not a radiator cap pressure issue, as that would (if I'm not mistaken) cause overheating regardless of if the air was on or not.


I have NOT checked the Thermostat - However, if the Thermostat was out, wouldn't it overheat if the AC was on or not?

Radiator Core not (visually) Blocked - As above, wouldn't it overheat regardless of if the AC was on?

Bad Water Pump: As the above two .. if it was bad, wouldn't it have issues regardless of AC?


Any assistance you could provide would be helpful, as Vegas + Car = 110 degrees with No AC :)


SIDE NOTE:
From time to time, the Check Engline light is popping on - but it's not STAYING on. It'll come on for about 5-10 minutes, then go off. Turning the car off will also "reset" The light. *Shrug*

1995 Dodge Intrepid ES -

It's overheating only when the AC is on. Turning the AC off quickly reduces the temp. This started Friday. It runs fine highway or surface, stop/go or cruising. ONLY when the AC comes on is there a problem.

Normal Causes of Overheating:
I don't believe it is the fans: The fan motors were replaced approximatly 2 weeks ago. The Driver side (single speed, I believe) fan is working fine. I haven't HEARD the passenger side fan, however after "setting" it and marking it, it is moved - so I can only assume it's working as well.

It is not a coolant level issue, as that's been checked, double checked and triple checked.

It is not a radiator cap pressure issue, as that would (if I'm not mistaken) cause overheating regardless of if the air was on or not.


I have NOT checked the Thermostat - However, if the Thermostat was out, wouldn't it overheat if the AC was on or not?

Radiator Core not (visually) Blocked - As above, wouldn't it overheat regardless of if the AC was on?

Bad Water Pump: As the above two .. if it was bad, wouldn't it have issues regardless of AC?


Any assistance you could provide would be helpful, as Vegas + Car = 110 degrees with No AC :)


SIDE NOTE:
From time to time, the Check Engline light is popping on - but it's not STAYING on. It'll come on for about 5-10 minutes, then go off. Turning the car off will also "reset" The light. *Shrug*

For check engine light coming on do the KEY DANCE. on/off, on/off, on The check engine light will flash showing codes that are stored. EXAMPLE- flash pause flash flash = code 12 battery disconnected in last 50 start cycles.

I believe when you turn on your AC both coolings fans should be working even at idle, check for a cooling fan RELAY in the Power Distribution Center in the engine compartment it may be located there. This site may help you. Take a look at the wiring diagrams.

http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c1528006ae36

good luck and post any codes

Okay. I changed the Thermostat today.... Well, Rather ... I opened up the Thermostat housing ... to find no thermostat. :P I put the new one in .. everything still works the same way. Runs fine without AC on. AC goes on and it overheats.

As for the Check Engine Light - The light wont' actually stay on, and the "key dance" doesn't seem to do or show anything at all.

Okay. I changed the Thermostat today.... Well, Rather ... I opened up the Thermostat housing ... to find no thermostat. :P I put the new one in .. everything still works the same way. Runs fine without AC on. AC goes on and it overheats.

As for the Check Engine Light - The light wont' actually stay on, and the "key dance" doesn't seem to do or show anything at all.

When you did the key dance did you turn the igntion switch on/off, on/off, on within 5 seconds without starting the engine? Even if there are not any codes stored in the PCM it should show a 55 code which means end of codes.

Have you checked all fuses and the high speed fan relay?

Have you used a fused jumper wire and checked to make sure both fans are working properly?

Why were the fans replaced in the first place, was it because of the problem you have now overheating?

When you did the key dance did you turn the igntion switch on/off, on/off, on within 5 seconds without starting the engine? Even if there are not any codes stored in the PCM it should show a 55 code which means end of codes.

Have you checked all fuses and the high speed fan relay?

Have you used a fused jumper wire and checked to make sure both fans are working properly?

Why were the fans replaced in the first place, was it because of the problem you have now overheating?

Okay ... It may not have been within 5 seconds - I will try it again in just a few and post anything new.

Fuses and all relays are fine - I've checked those several times.

The fan was replaced because the "Big" motor on the passenger side had gone out - It was cheaper to buy a whole new unit instead of just one fan, so that's what I did, replacing both. This was done ... Roughly 3 weeks ago, give or take.

Since then I have not directly re-checked the fans by hooking it to a jumper wire. That's my project for this evening when the engine cools down enough to touch it again since my last test. :)