Ive seen topic here before, but cant find them. My blazer is overheating when the AC is running, but cools when the heater is on. I flushed the radiator the best I could, but noticed the coolant isn't circulating like it should at normal running temps. Is this a problem with the water pump, the thermostat, or an air bubble in the cooling system? Thanks for the help.

 

If it only overheats when the A/C is running, I would suspect a restricted core exterior. Have you cleaned both the A/C condenser & radiator on the outside?

 

Thanks. I haven't, but I will. Hope this will help. We have had the blazer for about 5 months, so much to do with learning about it.

 

I'm not sure what is meant by cleaning the outside of those two items. Haven't ever thought of the outside of the AC condenser having anything to do with overheating the truck.

Can someone explain why this might help (and what I must do to properly clean it)? Do I need chemicals, just water, water/soap....? Just a wash with a rag or do I need a brush (soft/wire bristles)?

Thanks for the help, it's appreciated!

Todd

 

Use plastic bristles and a hose, no metal.

 

My 99 does the same...only with the ac on in stop and go traffic with the temps above 90 degrees outside...i just turn the heater on if the temp guage starts going over 210 by much...this drops it right back down while I sweat...I sweat all day at work so it doesnt bother me too much...I only drive it when I cant drive my motorcycle due to weather...I sorta cleaned mine and that didn't help any... I took it to the shop when I was thinking about buying it and had them check it over real good. they replaced the water pump and flushed the system among some other not cooling system repairs...yesterday was 89-90 and I drove 30 miles home with the ac on and it never got over 210 but I was not in stop and go traffic...thinking its just going to be something to deal with in July and August and should be fine the rest of the year...hopefully! open for other suggestions though...thought maybe fan clutch but the mechanic said it seemed fine and there were no leaks from the pressure test and its never low on fluid..

 

take the top have of the radiator shroud off easy to do and look in between the radiator and condenser and you will find dirt and leaves garbage wash out with degreaser and hose dont try to brush off you can bend fins and dont rubb with hands very fragile and use a grabber tool or compressed air works thats what happened to mine started to run hot last year and i cleaned it been ok every since you my have other problems but i would start their first

 

I have a 98 blazer and I had that exact poroblem I flushed it aswell but it still overheated really bad. I went to the auto store and purchased " Water-wetter" and it lowered to the normal operating temp. How it helped so well I have no idea, but it worked.

 

sorry mis spelled half their needs to be good air flow across the condenser and radiator for engine to cool right thats why its over heating dosent cost anything to look