Intermittent heat in an 02 Blazer
 

I have recently been having problems losing heat in my Blazer. I changed the t-stat twice now, it worked for a few days, maybe even a few weeks then it would blow luke warm air. There are times where the heat works, but it is intermittent.I had the system evac. for air and the coolant level is fine. TheTemp gaugerises to 180-210 at normal running temp.The only pertinant thing I can think of is a verysmall leak over the past few months of what appeared and smelledto be water over the front passenger side of the engine. I was reading some forums about clogged heater cores, bad heater cores etc. I can't place my hand on it... What should I do?

RE: Intermittent heat in an 02 Blazer
 

Sounds like your heater core is going bad and has a crack in it. If you are still running Dexcool, it is most likey oxidizing in the area that you have a crack and causing a clog. The leak in the passenger side you are describing might be small and intermittent becuase the dexcool oxidizes and solidifies, covering the crack but also clogging your heater core. Flushing you heater core should temporarily restore the heat, but unless you fix the leak, you will loose heat again.

Out of curiosity, why did you replace the t-stat? was it becuase it was sticking and when you opened it up it was all gunked up?

RE: Intermittent heat in an 02 Blazer
 

Thanks for the thought... how would I go about flushing the heater core?

As far as why I chose to change the t-stat... well I am no mechanic, I lost heat, it was cheap so I gave it a try...It looked pretty cleen when I changed the first one. The second one was a cheap POS, therefore when I lost heat the second time I thought the t-stat may have been faulty... Trial and error i guess...

RE: Intermittent heat in an 02 Blazer
 

How much is a new heater core, and the difficulty to install?

RE: Intermittent heat in an 02 Blazer
 

mine is doing the same, had the cooling system and heatercore flushed heat came back for 3 weeks now its gone again. I get no change in temp from the ventswhen I turn the temp dial to the coldest setting or the hottest setting, it stays luke warm. no coolant leaks that I can see. I am replacing the hvac in the dash to see if its faulty, I would think there should be a temp change when turning it to the coldest setting.... btw its a 2001 trailblazer.

RE: Intermittent heat in an 02 Blazer
 

I have a 2002 blazer and its doing the same thing. The temprature gauge says its 195 deg., but no heat comes out of the vents. I checked the hoses going into and out of the heater core and the one is hot and the other is cold. So I would assume that the heater core is plugged. But then the next time I get in it to drive it it will blow some warm air and if you stop and let it idle for 5 minutes it goes back tyo blowing cold air. My question is what controls the temprature of the air? Is it some thing that just mixes hot and cold air or is it something that controls the flow of antifreeze through the heater core.

RE: Intermittent heat in an 02 Blazer
 

Heater cores have always beena full flow item, they flow all the coolant that is directed to them. Thereare no restrictions in the heater core to change the heat coming into the cabin. There is a door behind the dash that mixes cold and warm air...

RE: Intermittent heat in an 02 Blazer
 

is the water leak on the actual engine or just near the fire wall if it is over the engine then ur problem would most likely be a heater hose if it is at the firewall then u either have a loose hose clamp on ur heater core or ur heater core is leaking. if the heater core is leaking it would be all over ur floor on the pass side most likely and u probably would have noticed it. my guess is your heater core is junk and u should have it replaced its not easy though cuz you have to remove the ENTIRE DASH BOARD and thats no exaggeration good luck

RE: Intermittent heat in an 02 Blazer
 

correct me if im wrong. there is a heater control valve between the heater core and the radiator that meters the amount of coolant that flows to the heater core. it works just like a t-stat only for the core instead of the radiator. a friend of mine had this same problem inhis 96 chevy box van and put that part in and it worked like new. its cheap and easy. well worth it before doing the heater core thats no easy task. i dont know ifmy name for the part is right but thats what i was told it is called.

RE: Intermittent heat in an 00 Blazer LT
 

Hi everyone

I have the same problem. When i'm on the road the heat goes on and off. I have a Blazer 2000 LT (Automatic : heater/air conditioning)

I have the truck manual and they say that's better to go at the dealer if i have a automatic system.

What do you think ?