I have a 1997 Chevrolet Blazer and the heater had been malfunctioning where it would be blowing heat then all of the sudden stop blowing and then begin blowing again without touching the control dial.That i could actually deal with but now it is not blowing heat at all.It seems to have took a dump at the worst possible time (on a normal 3 hour 190 mile trip from Somerset Pa. to Glen Burnie Md)and of course it had to be snowing, sleeting and freezing rain.We had a little cigarette lighter plug in accessory heater with us and attempted to keep the windshield from icing up but that did absolutely no good.After 1540 stops to manually de-ice the windshield and wipers, and 6 hours later we finished the trip.Kinda seemed like Gilligans Island “3 hour tour … from hell ! ! !” We have tried every dial on the dash for heater controls and nothing at all.We are on a VERY very tight budget due to me getting fired from my job due to an on the job injury severely hurting my back and can’t spend a whole lot(almost nothing)in order to fix this problem so basically i need to fix it with the correct parts the first time and not guess as to what it could be(i am kinda good at guessing but right now that could be costly for me).To sum it up if anyone knows exactly what i would have to buy or fix in order to get my toes thawed out and keep the heat going on this vehicle i would appreciate the info so very much.We thank you very much ~Scott & Amber (& our toes)
I hesitate to answer because you want to know exactly what the problem is, not what I could be, To tell you exactly I would need max. 30min hands on time.
Your statement about the trouble is a little confusing to me. Are saying the blower motor is intermittent or the defroster mode goes from hot to cold? If your are saying the air goes from from hot to cold the first thing to check is the coolant level. If you are saying the blower motor is intermittent then you might check the relay for a problem there first.
The first step is free and easy. You want to verify that hot coolant is going into and out of the heater core. With the engine hot on the temp gauge, the heater set to hot and the fan on high, go under the hood and feel both hoses for the core at the firewall. Are they hot?
Find the blower motor and its power connection. Measure for voltage at that connector (while the motor is still plugged in). If there’s power on the connector and the blower isn’t blowing, then you need a new blower motor. Probably about $50.
The blower worked intermitantly worked sometimes then stopped then started again later but last time it didn’t come back on at all
Yep, its kind of hard to tell exactly what the problem is from 2000 miles away. Sounds like either the blower itself has gone south, the switch, or connections/wiring. You can also put 12 volts right to the motor and if it runs, the motor is ok and its something else. If it doesn’t run its the blower motor. GMs are famous for blower problems and a new rebuilt one from NAPA would be about $35. You can get one from a junk yard for quite a bit less money. If you are really broke, you can drill out the rivets, take the motor apart and fix it temporarily if it is just bearings or brushes. I did that once and got another year out of it.
Is the method of replacing the blower motor clear to you? do you know where the motor is? You access the blower motor of your year model S-Blazer from the engine compartment (some years required cutting the housing to get them out,there are indentations on the housing indicating where to cut.
I am not ready to say it’s not a control head failure.