Engine Overheats and Air Conditioner stops when ambient temperature exceeds 90 degrees

infiniti
airconditioning
i30

#1

My 2001 Infiniti I30 overheats when the air conditioner is on and the ambient temperature is above 90 degrees. At the same time the air conditioner stops blowing cold air.

What may be wrong?


#2

A great many things might be wrong. You need to provide more information to get a better answer.
Ignore the fact that the AC stops working. Your engine is attempting to protect itself by disabling the AC when it is overheating. If you want your car to last, you should stop the car and the engine before it gets hot enough for this to happen. You are flirting with disaster here.

Does it overheat when you are sitting still?
Does it overheat in stop and go traffic?
Does it overheat while you are going 50 MPH or faster?

If you turn the blower on high and set the climate control for full heat, does the engine temperature come down?

Have you checked your coolant level?
Do you have to add coolant every so often?
What is the condition of your coolant? (Clean or dirty, correct mix of anti-freeze)
When was the last time you had the coolant changed? Was the thermostat changed?

Have you checked to see if the fan is running?
Does the fan switch to high speed when the AC is turned on? (Or, do you have two fans?)


#3

Thanks, it is rare that I drive with air conditioner, but with the daily temperatures in excess of 95 degrees I am now encountering a problem.

I’ll answer the ones I can:

Does it overheat when you are sitting still? NO
Does it overheat in stop and go traffic? NO
Does it overheat while you are going 50 MPH or faster? YES, but it also overheats when I am going slower if the ambient temperature exceeds 90 degrees and I have been driving awhile.

If you turn the blower on high and set the climate control for full heat, does the engine temperature come down? YES

Have you checked your coolant level? YES, It is OK.
Do you have to add coolant every so often? Rarely.
What is the condition of your coolant? (Clean or dirty, correct mix of anti-freeze) How can I tell if it is clean. I add the coolant directly from the bottle - no mixing.
When was the last time you had the coolant changed? Was the thermostat changed? The coolant was last changed in Sept 2008 when the radiator was replaced. I recently had an additional “radiator” added to cool my transmission.

Have you checked to see if the fan is running? Inside fans are working OK.
Does the fan switch to high speed when the AC is turned on? (Or, do you have two fans?)
The fan automatically switches speed depending upon the temperature that is set.


#4

I am asking about the engine cooling fan(s), not the blower for the AC.

Is the anti-freeze that you are adding premixed? Otherwise, your 50/50 mix of antifreeze to water (which is ideal) is being compromised. (Not so much as to cause overheating.)


#5

I think that you should have the car tested for possible head gasket failure.


#6

You need a full flush and fill of the cooling system, a new thermostat and new radiator cap. I believe this will correct most of your problems.

Are you sure the coolant was changed when the radiator was replaced? I ask because I had a shop replace the radiator once under warranty, and watched them re-use the old coolant. I bitched and had to pay for them to use new, so I just want to warn you that it is not safe to assume they replace with new on a radiator replacement.

The same goes for the radiator cap and thermostat. The radiator cap may have been replaced, maybe not. Chances are good the thermostat was not replaced.

Another sad radiator story: I was in an accident where the radiator was punctured and needed to be replaced. Insurance was covering the damage, but I asked about replacing the radiator hoses (2) while they did the work. They quoted me $200, basically because they were using book labor rates. I tried to argue book rates didn’t apply, because the hoses were half being removed to do the radiator. I was willing to pay for the hoses and a bit more to fully detach the old hoses, but they refused to budge. I refused their quote.


#7

This may or may not help, but it won’t cost you anything to give it a try. Obviously, the radiator can’t move enough heat out of the system at the higher temperature and the load of the airconditioner. It may be that the radiator is externally clogged with bugs and debris. When the engine is cool, take a garden hose with a nozzle and from under the hood, squirt a stream of water through the radiator and out the grille. Alternatively, you could use compressed air. If the fins of the radiator are clogged, the fans can’t pull enough air through the radiator to remove the heat.


#8

Thanks for your considerate and detailed responses. I feel that I’m better prepared to approach this.


#9

I heeded your advice - replaced the thermostat and then all the coolant and then the radiator. Problem solved.

Thanks again for all of the detailed help.