Overheating?

[MVSHO]

My 95 MTX runs right around the R-M on the temp gauge while driving. Sitting in traffic, it gets to the upper line just below the red. It never passes it, though. When i start driving, it will go back to the normal range. What could be causing this?

Also, when using the vent it will blow normal temp air for a while, then get really hot all of a sudden. Any help would be appreciated.

 

[sdpatt]

Verify that the radiator cooling fan will run when you select AUTO on the climate control. If the fan doesn't run, the motor is likely worn. If it does run, when you select AUTO, does it run when the temperature guage reaches the "H" mark? It should engage far below that temperature.

 

[MOSHO92]

Yeah, check the fan first. There could also be a lot of sludge in your coolant that keeps it from circulating until you rev the engine(waterpump). Just a thought.

 

[MVSHO]

One thing i should add is that when the gauge gets near the top while idling in traffic, it will stay there for a minute then it will go back down to normal then go back up again after a minute or two. to me, that means the fan is coming on but a little late.

 

[projectSHO89]

The 95 MTX uses a two speed cooling fan.

It sounds like the low speed portion of yours is not working.

Tyr this:

Turn climate control to off

Start engine (cold)

Observe cooling fan. It should be off.

Turn climate control to MAX. The cooling fan should now be on in HIGH speed operation. Note the noise and airflow of the fan for future comparison.

Turn climate control back off.

Allow the engine to idle to operating temperature while observing the temp guage.

If the guage goes all the way to "almost" hot when the fan comes on, observe the fan speed. Was it like it was earlier with the AC running?

If so, the fan is only working in High speed.

If this is your case, you may have a defective relay in the CCRM, a fault in the PCM, defective motor, the ECT, or the wiring harness that connects it all together. You will definiately need more diagnostic work.

Steve