TCCoA Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
654 Posts
Discussion Starter #1
My car tries to overheat on 90 degree + days with the AC on. And there are far too many of those in Texas.

The history:

Thermostat went out about 4 years ago. The car only overheats on hot days, so I don't think that's it.

The factory fan took one for the team on a hot summer day about 3 years ago. I replaced it with one from Oreily (I think). Nothing aftermarket, just a new fan motor. (It's scary to be trapped at a stoplight with black smoke rolling out from under your hood...)

Two years ago I had the radiator rodded out on a whim. No help whatsoever...

Last week I replaced the multi-function relay as it seems to be a common issue. No help there either...

My thoughts are: How do I verify that the high speed circuit is working? And has anyone had an issue with a replacement fan motor? From what I can tell the fan is doing the best it can. Could it be an issue with my AC possibly? It's never been serviced, but It blows cold air until I have to turn it off.

I've never let it get hot enough to boil over. It doesn't lose any coolant and it's only the hot HOT summer days that it runs hot.

Any thoughts?
 

·
Registered
Joined
·
2,639 Posts
does it only over heat when sitting still or while up to speed also? is the fins on the radiator and condensor clear of dirt and debri
 

·
Registered
Joined
·
173 Posts
coolant might not be at the right mixture also check your heater core it may be plugged or partially plugged causing poor circulation. If you believe the fan is the issue hook up a manual switch and see what it does with that. Also make sure your thermostat is working properly and check to make sure your fins in the radiator are not corroded. Also it may not be a bad idea to drain and refill the system as a just in case.
 

·
Registered
Joined
·
654 Posts
Discussion Starter #5
The radiator has been removed, disassembled, rodded and boiled out. The fins are clean and straight. The water pump is still the factory pump. It's been my experience that water pumps don't stop pumping, they just start leaking. Mine doesn't leak, so I assume it's OK.

The last time I changed the coolant it didn't seem to help any. I think I'll take it down and get it properly flushed.

Can anyone give me a diagram/ voltage that should be at the fan for the high speed circuit?

Thanks
 

·
Registered
Joined
·
1,252 Posts
The PCM and CCRM determine when the fan should turn on and at what speed. Fan always runs with the A/C on other than that depends on the Temp. It should turn on low at around 190 with a stock tune. Not sure about the high speed.

There are 3 wires going to the fan - black (ground), blue should be low and brown/orange stripe should be high. If your colors differ, check for voltage between the black and the other 2 when the car is cool and the A/C is on that will be low speed.

Never saw an answer as to if this happens at speed on the highway. Fan has little effect then. A/C will add quite a bit of heat at lights just from the amount of heat coming off the condenser.

Water pumps usually work or don't or leak. Stock pumps seem to go quite a while.

Other than that since you had the radiator cleaned, I would suggest getting a flush tee and a bottle of something like super flush as your cooling the cooling passages in the engine might be gunked up. Follow the directions to clean it out, flush good with the garden hose.

Let it cool and drain out as much water as you can with the radiator drain and dump the degas bottle. Add full strength coolant to the radiator and degas bottle.

Good luck.
 

·
Super Moderator
Joined
·
10,576 Posts
Flush the heater core, and see what comes out of it; if it really looks nasty, bypass it with a piece of hose and see if the problem goes away.

IMO, It is almost impossible to flush the core without hooking directly to it...
 

·
Newbie
Joined
·
5,650 Posts
If you want to test that the high speed circuit works, unplug the coolant temp sensor while the car is running. This is the sensor on the driver's side of the coolant crossover. The low-speed circuit is supposed to be activated when the A/C is on or when the coolant reaches 222* F. The high-speed circuit is supposed to be activated if the coolant reaches 228* F or if the coolant temperature doesn't decrease after the low-speed circuit has been activated for a set amount of time.
 
1 - 8 of 8 Posts
Top