Roman. GS Runs Great but annoying problem with my Van.

[Anonymous]

This is not a GS problem. My GS runs like a dream. But I do have two little annoying problems with my 1998 GMC Safari that I would like to share with you and maybe someone would be able to help me find the trouble. These are probably easy fixes if you know where to look.

#1. My fan motor (heating and air conditioning) only works on the 3 low speeds but doesn’t work on the highest setting. What do you think the problem is and where can I find it.


#2. Temperature control doesn’t seem to work unless the outside air temperature drops below a certain reading. Last summer and this summer I could not get any heat out of the vents to defog my windshield, but as soon as the temperature drops below a certain reading it starts to blow warm air. This one really gets me thinking, :? :? any ideas. I know that there is some sort of temperature switch that controls the operation of the air-conditioner but I really don’t think that there is one for the heater.

Any help or suggestions would be greatly appreciated.

Thanks

[kevan]

VAn Troubles

The fan speed is usually controlled by a wire resitor that is mounted in the air flow of the heater duct work. If you can find a small block mounted in the ductwork, held in place by a screw or screws with a connector on it. Pull it out and inside there would be a number of wires wrapped in coils of various diameters attached to the connector. These wires break and therefore you lose you fan speeds.

I hope this helps.

Kevan

[zstanisi]

Hey Roman, sorry to hear you've got problems. I have a Haynes manual for your van, can lend you to have a look. Not sure if they explained heating system in details, can have a look into it today and see what I can find. Ideas:

#1. It could be a switch or the connection or the fan itself. Don't think you would have anything else in that circuit.

#2. Not sure I have idea for the second one, but it sounds like some temperature sensor.

[focus frenzy]

easy problems
#1 your blower high speed relay is bad, the lower three speeds go through the blower resistor, high speed is controlled by a relay that bypasses the resistor, it will be located under the hood close to the blower motor.
it will be a black 2 inch by 2 inch by two inch square plastic thing, it should have 5 wires going in the bottom plug, one or two purple and the others green and pink.

#2 why do you want heat in the summer??? it is 44C 109F here right now!! I have no desire for heat!!

modern vehicles are built to save our selfs from our selfs, when you put the control in the defrost/defog position it will turn the ac on to remove moisture from the air and clear the inside of the windshield with out needing hot air, frosted windshields are not a problem in the summer time so they programed it to not allow heat when it is warm out so If a child is left in the van with the ignition on and the ac going, they cannot accidentaly turn it to heat and bake them selfs.

[Anonymous]

Wow!

GS guys know so much.

Leon,

I will look for the relay today after I finish my time in the work place.
What you say about the heat makes a hell of a lot of sense to me but I really don’t think that it allows heat to blow at a reasonable outdoor temperature. It could be a cool November morning about 45deg F my wife is complaining she’s cold, I turn on the heat control to warm up the van and nothing happens. It will eventually blow warm air when the outdoor temperature reaches around 32 deg F. This doesn’t sound right to me. I’m guessing that there is some sort of switch that isn’t working properly but I don’t know for sure if there is such a switch and if there is I don’t know where to find it. If you or anybody else should have any ides, that would make one GS owner very happy.

Thanks for all your help.

Roman.

[Redman]

#1. I have had that blower relay fail on my Chevy Astro van, and I have had bad connectors on the bottom of that relay melt the insulation off wires. Maybe look at those connectors. No need to look at the resister wire coils in duct, those are for the lower speeds like Focus so well described.

[Anonymous]

Thanks Redman,

Could you please give me a better idea of where the relay is located? I'm guessing that it's the one just behind the washer and coolant containers.

Roman.

[Redman]

As far as location of relay, I cant really say on your van. On my Astro it was amoungst a few other relays in a row on upper left side of firewall, which was also close to the blower and the resistor coils. That also seems to fit the description that Focus gave. Maybe another way to find it would be to follow the wire from blower and/or the wires from resistor coils.

[Anonymous]

Roman - My vote is that the guys are dead on about the high blower relay. Amongst other things, you may be able to follow a large purple wire directly from the proper relay to the blower motor. As far as the "no heat" concern, I quit working on GMC's in '94 and I can't think of anything used at that time which would cause this. However, based on general automotive experience with this sort of thing, look for some sort of "switching valve" or "sensor" in the heater hoses. Anything unusual looking which is mounted as part of the heater hoses is suspect. Check the connections, which could be vacuum or electrical, and experiment with unhooking it to see what type of response you get from the system. Feel the hoses to see if a change in temperature occurs before and after the "valve/sensor" unit. Just a shot in the dark, but maybe it will get you headed in the right direction. I will also try researching this a little more, but won't be on line again for a few days.