I get absolutely no hot air from my heat system. How do I test if it's a bad core or a bad thermostat? The thermostat is an easy fix so I could do process of elimination, but I just wanted to know if there was a way to figure out what's wrong before I do anything. Thanks.
MW
I found this at about.com, but I'm hoping for something that wouldn't require pulling something out yet.
"The best way to test a thermostat is to place it in a pot of boiling water on the stove. As it heats up to its rated temperature, its valve should open about an inch. If it doesn't, then throw it out and get a new one."
MW
On Mon, 28 Nov 2005 21:40:15 +0000, M White rearranged some electrons to form:
It might have nothing to do with the cooling system... maybe the temperature door is not working. Warm up the engine and put your hand on the heater hose. If it's hot, then the problem has nothing to do with the core or the thermostat.
If the engine doesn't warm up, then maybe your thermostat is stuck open.
Yes that test will work, but if you intend to go through the trouble of taking the t-stat out, why not just put in a new one? Cheap insurance! If the heater hoses are hot, once the engine is warm, maybe the blend door not functioning and/or the core is leaking/clogged. The hinges on those doors have the nasty habit of breaking. Your truck is 10+ yrs old. The lifespan of the core is right around 10yrs. Check the operation of the blend-door actuator. If it is cable operated, unhook the cable and manually turn the lever....the only sound you should hear is a quiet 'thump' when the door closes off the heater core part of the plenum. The better way to tell is to remove the heater-core cover in the plenum and check the door for proper operation.....with that cover off you can also tell if the core is a leaker too. A new core and t-stat is under $50. Once they are replaced you are good for another 10yrs or so!
Hope this helps some.....
Dave S(Texas)
I can't tell you how much I appreciate everyone's feedback, including those who have e-mailed me directly. I have pulled out the t-stat. I had the same thoughts and am going to just put a new stainless steel one in. As it turns out, the current t-stat looks like it was working just fine.
I am going to purchase a manual to find out what where all of these parts are so I can inspect it the way you mention.
MW
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