Vent system Problem

[Istariel]

New voice here...trying desperately to find a fix for my problem. My 1994 S-10 Blazer 4-door 2wd/4wd automatic, top of the line for that year, seems to be working fine, but has a problem in the vent system. No matter what its on -- vent, A/C, heater, haven't tried defrost yet as this problem appeared in summer -- at some random point the air coming from the vents begins to stink in a hot, burning type of smell.

I can't tell if it smells electrical, plastic, or what, mostly because I don't know how to tell the difference, and it never does it on demand or when I have witnesses in the vehicle. If I don't turn the system off right away, I then get white or light gray smoke from the fan control switch opening. I'm afraid to run the vent system for fear of creating a fire...and as we are now in Fall headed toward Winter, I need my defrost and it's getting cold!

My mechanic has checked the system both from the engine compartment and from inside the cab, removing the dash board so that he can check the tubes for stray leaves, etc. and found nothing; nor has removing the fan motor and testing it resulted in any obvious display of the problem. He also cannot seem to get the car to create the smell and smoke by running it for long periods. There also seems to be no apparent damage to any wiring.

The only other thing that might be related (but may be a new problem in itself because the car has a history of wiper problems) is that when the turn signal is used, the front windshield wipers will make one swipe and return to the rest position. This usually happens when turning right, but has happened once in turning left.

If anyone can give me a clue on this that I can pass on to my mechanic, I would sure appreciate it. Thanks!

[MT-2500]

Originally Posted by Istariel

New voice here...trying desperately to find a fix for my problem. My 1994 S-10 Blazer 4-door 2wd/4wd automatic, top of the line for that year, seems to be working fine, but has a problem in the vent system. No matter what its on -- vent, A/C, heater, haven't tried defrost yet as this problem appeared in summer -- at some random point the air coming from the vents begins to stink in a hot, burning type of smell.

I can't tell if it smells electrical, plastic, or what, mostly because I don't know how to tell the difference, and it never does it on demand or when I have witnesses in the vehicle. If I don't turn the system off right away, I then get white or light gray smoke from the fan control switch opening. I'm afraid to run the vent system for fear of creating a fire...and as we are now in Fall headed toward Winter, I need my defrost and it's getting cold!

My mechanic has checked the system both from the engine compartment and from inside the cab, removing the dash board so that he can check the tubes for stray leaves, etc. and found nothing; nor has removing the fan motor and testing it resulted in any obvious display of the problem. He also cannot seem to get the car to create the smell and smoke by running it for long periods. There also seems to be no apparent damage to any wiring.

The only other thing that might be related (but may be a new problem in itself because the car has a history of wiper problems) is that when the turn signal is used, the front windshield wipers will make one swipe and return to the rest position. This usually happens when turning right, but has happened once in turning left.

If anyone can give me a clue on this that I can pass on to my mechanic, I would sure appreciate it. Thanks!

I would check heater core for leaking antifreeze.
That old green stuff can even kill you if you breath the fumes from a heater core leak.

White steam or sweet smell or fogged windshield when ac/heater or defrost or vents are first turned on.
oes it lose any coolant?
Any wet carpet or wet spots under heater?

Pressure test coolant system and see it make any smoke or smell from heater.
Also they make coolant dye for cooolant system toshow where you have a leak?

For smoke out of heater controls pull controls part way out of dash and look for where smoke is comming from.

Good Luck and let us know how it goes.

[Istariel]

No signs of any leaking antifreeze; my mechanic checks regularly when the Blazer has an oil change for any other problems as it's an older car. The smell that comes out when the vents are used is a hot, acrid, burning type one, and the only fogginess (besides cold weather sorts now) is the gradual buildup of slight A/C deposits that all cars get after the system is used for a season. We haven't seen any coolant leaks or wet spots on the carpet either. This seems to be rooted in the fan system -- motor, belt, fan blade, controls for same, but we aren't sure.

As of yet, my poor beleaguered mechanic has not been able to actually get the dash off like he said he would try to do because he is SO busy right now with everybody and their brother wanting their cars fixed/winterized, not to mention my own busy life -- I just got another pet-sitting job up a draw with a road I don't dare risk my mother's little '94 Toyota Tercel on because that car bottoms out so easily (very rough road needing Blazer clearance and in winter possibly 4WD) I won't be able to get the car into to be looked at again until after the 9th. So I'm going to be taking all suggestions I get into him with the car when I finally can get it in. I will certainly keep things up to date here. Thanks for the suggestions!

[MT-2500]

If the odor and smoke is not electrical smell or oder.
There is several TSB's on odor on start up.

They involve a deodorizing kit for AC evaporator and a after burner on fan control.

[Istariel]

Honestly, I couldn't tell if it's electric or what being as I don't know what said odors smell like, and those that do have not been in the car when it happens! And naturally, it won't produce on demand !

Since this happens at random times (once within a few moments of start up and the other times anywhere between five minutes to half an hour to not showing until almost three days of use since given the okay to try and run it after a check), I'm really not sure what this could be save some crossed wires somewhere maybe if it's not the fan system itself, not involving heat or A/C, just air movement...

[MT-2500]

Originally Posted by Istariel

Honestly, I couldn't tell if it's electric or what being as I don't know what said odors smell like, and those that do have not been in the car when it happens! And naturally, it won't produce on demand !

Since this happens at random times (once within a few moments of start up and the other times anywhere between five minutes to half an hour to not showing until almost three days of use since given the okay to try and run it after a check), I'm really not sure what this could be save some crossed wires somewhere maybe if it's not the fan system itself, not involving heat or A/C, just air movement...

Check with your mechanic and run the tsb by him and see if he thinks the deodorzing kit would hlep.
Good luck