car trouble/overheating

[toant103]

Whenever i use my AC, the temperature would get to the 80% mark. Any suggestion to what the problem is? The car is fine if i don't use the AC.

I have 1990 Mazda Protege.

 

[Pepsi90919]

check coolant condition. suspect water pump, thermostat or fan relay.

 

[skyking]

The AC dondenser is located in front of your radiator. when you turn the AC on, it heats the cooling air for the radiator dramatically.
Possible causes, in order of cheapest fix/easiest fix:
1) malfunctioning thermstat. It may not be opening up sufficiently, and the problem is not noticeable until you run the AC.
2) clogged radiator.
3) bad electric cooling fan/ sensor.
4)failing waterpump. depending on design, it may have eroded parts inside which no longer move the water. Most unlikely, but possible
5) AC problem. Least likely, since you have not said is isn't working.
6) automatic transmission problem. Unlikely, but the tranny uses the radiator to cool the fluid.

 

[Vegito]

Check ur compressor when the AC is on, you might not even have any freon left !!!! thats a big checkie, also check the belts !!! water pump maybe good but belt maybe not be.. check everything.

 

[PsychoAndy]

Originally posted by: forcesho
Check ur compressor when the AC is on, you might not even have any freon left !!!! thats a big checkie, also check the belts !!! water pump maybe good but belt maybe not be.. check everything.

Why the hell would an uncharged system lead to engine overheating? The last time I checked om my car, the compressor is self contained and its cooling and lubrication is determined by the compressor oil and the liquid r12. On the same note, why would a malfunctioning water pump magically not stay working at the same time as the compressor? He has established that the car runs fine normally without the A/C running.

I'm thinking there is a problem with the fan relay or the fan itself. Turn your A/C off and check if all the fans are running. They may or may not be. Turn the A/C on and they should still be running, or turn on if they havent already. My electric fans dont even kick on when the needle is pointing at H, however once you hit the low switch and activate the compressor, both of them fire up.

 

[toant103]

Originally posted by: skyking
The AC dondenser is located in front of your radiator. when you turn the AC on, it heats the cooling air for the radiator dramatically.
Possible causes, in order of cheapest fix/easiest fix:

6) automatic transmission problem. Unlikely, but the tranny uses the radiator to cool the fluid.

I have a 5 speed manual. The fan for the radiator and ac kick in.

THanx for all the suggestion. For now, i'll just use my car with no AC.

 

[Pacfanweb]

My first thought was that your cooling fan(s) weren't working, but you said they were. My next question: Do they run the WHOLE time the a/c is on? Or do they kick on and off? They should run the whole time the A/C is on.

Next, how hot does the car run normally? It sounds like the cooling system isn't working efficiently.

Yes, the condenser is in front of the radiator, and gets hot, but that shouldn't be a problem if the cooling system is working properly.

How about when you're driving strictly at highway speeds? Does it cool ok then but heats up in town? (with the A/C on, I mean)

If all these things are normal, then we're back to cooling system basics. Thermostat. Water pump. Restriction. And the classic, coolant level.
There is no way to truly test the thermostat without physically removing is and putting it in hot water. They are dirt cheap, just replace it and see if it helps.
That is the first step any mechanic would take if all the stuff I described above checks out ok.

Let me know if you need any more help. You can PM if you want, and I can ask specific questions that will help diagnose the problem.

On the same note, why would a malfunctioning water pump magically not stay working at the same time as the compressor? He has established that the car runs fine normally without the A/C running.

If the impeller is slipping on the pump, it may circulate enough water to cool without the A/C on, but not enough with the added load. Rare, but I've seen it.

And being out of freon will cause the A/C to not work. The compressor will never cut on. Even if it did, you wouldn't have any heat exchange, therefore, no overheating problem.

 

[toant103]

the AC work well. Normally, my car temp is at 50%. The temperature sensor would rise when the AC is on during city driving and highway driving.

 

[Thegonagle]

If the coolant and thermostat check out, and there are no leaks, then the age of your vehicle suggests that the radiator is on the way out.

It's probably around $150 for a brand new replacement brand.

Changing it should be almost as easy as an oil change, so you needn't worry about paying someone else for labor, in case you didn't know. 🙂

 

[Pacfanweb]

Assuming the engine is full of coolant, go ahead and replace the thermostat first. It's the cheapest thing you can do.

Whether the cooling fans are running is irrelevant if it heats up at highway speeds, too.

Also, what does the coolant look like? If it's really nasty, you may want to have the cooling system flushed along with replacing the thermostat.

 

[toant103]

Originally posted by: Pacfanweb
Assuming the engine is full of coolant, go ahead and replace the thermostat first. It's the cheapest thing you can do.

Whether the cooling fans are running is irrelevant if it heats up at highway speeds, too.

Also, what does the coolant look like? If it's really nasty, you may want to have the cooling system flushed along with replacing the thermostat.

engine coolant is nice and green.

 

[toant103]

Originally posted by: Garfang
If the coolant and thermostat check out, and there are no leaks, then the age of your vehicle suggests that the radiator is on the way out.

It's probably around $150 for a brand new replacement brand.

Changing it should be almost as easy as an oil change, so you needn't worry about paying someone else for labor, in case you didn't know. 🙂

IT might be easy for you to change the radiator, but i have no experience in replacing anything for my car. But i better start soon though.

Thanks for the advice

 

[Skawttey]

This could be perfrctly normal depending on how hot it is outside and other factors. Are you sitting still or moving? Are you driving up a hill when it gets too hot?

 

[skyking]

let us know how it goes. I just replaced the thermostat on that 319,000 mile 626 the other day. It had failed completely.
If you do pull out the thermostat, place it in a pan of water on the stove, and heat it to boiling. If it is OK, you will see it open way up. If not, then you know for sure that it was bogus. This is very helpful to know. Often people will keep throwing parts at a problem, and never really know what fixed it.

edit spelling