Over heating while a/c is on

[xj94]

My "94 only over heats when the a/c is running, i replaced the radiator, water pump and t-stat last year. i flushed to radiator about 3 weeks ago and changed the t-stat. the fan appears to turn on as it should. :bang:

[Mudderoy]

My "94 only over heats when the a/c is running, i replaced the radiator, water pump and t-stat last year. i flushed to radiator about 3 weeks ago and changed the t-stat. the fan appears to turn on as it should. :bang:

Hmmm I was going to say electric fan. What is the temp with the A/C off?

[Cheromaniac]

This is quite a common problem with the onset of summer. The first thing to do is check the tension in the drivebelt. There should be no more than 1/2" of deflection and you shouldn't be able to twist the belt more than 90 degrees along its longest free length.
A slack belt will slip on the water pump pulley as soon as you subject it to the extra load of the AC compressor and that can cause the engine to run hotter.

[nickyg]

Have you checked the mechanical fan clutch? (fan on the passenger side)

with the engine OFF and warm, give the fan blade a spin by hand.........it should stop in less than one revolution, if it's still good, keeps spinning if bad. A viscous fan clutch is never locked.......if it is, that's bad.

[xj94]

well I have this little problem with the temp gauge only reading a hair past the first mark but my thermal scanner reads 180/190


Hmmm I was going to say electric fan. What is the temp with the A/C off?

[xj94]

I'll check on that on Monday thanks




This is quite a common problem with the onset of summer. The first thing to do is check the tension in the drivebelt. There should be no more than 1/2" of deflection and you shouldn't be able to twist the belt more than 90 degrees along its longest free length.
A slack belt will slip on the water pump pulley as soon as you subject it to the extra load of the AC compressor and that can cause the engine to run hotter.

[xj94]

first order of the day, thanks




Have you checked the mechanical fan clutch? (fan on the passenger side)

with the engine OFF and warm, give the fan blade a spin by hand.........it should stop in less than one revolution, if it's still good, keeps spinning if bad. A viscous fan clutch is never locked.......if it is, that's bad.

[xj94]

changed temp sensor, temp sender and fan clutch. temp gauge now works and no more coolant bubbling, fan clutch was shot but reads very high. reads half way to hot mark and sometimes dip down into the hot, i checked under the hood with a thermo reader at it reads 198 to 205 though.





Have you checked the mechanical fan clutch? (fan on the passenger side)

with the engine OFF and warm, give the fan blade a spin by hand.........it should stop in less than one revolution, if it's still good, keeps spinning if bad. A viscous fan clutch is never locked.......if it is, that's bad.

[4.3LXJ]

We have another member here that has an errant temp gauge too.

[Brasscatz]

Your condenser heats up quite a bit when the a/c is on, and that's the smaller/thinner radiator looking thing in front of the actual radiator. Check for blockages in the fins of both condenser and radiator. Also check for bent fins that'll restrict air flow