Fan Blower Switch in Dash - Does Not Work on just Speed "4" & No A/C

On my 90 Golf the speed "4" suddenly does not work. It works on all the other speeds (1-3) just not 4. Did some digging, is this mostly likely the switch in the dash, the relay or the fan motor?

Last day or so its been really hot and I went to to turn on the AC and noticed that no cold air was coming out nor could I hear the compressor running. Usually the engine dips a bit when its on.

Well I went to my Bentley manual (page 254) and started looking at the wiring diagrams. It appears that on "4" the circuit runs from the switch through the AC relay and than down to the fan. It does not go directly through the fan. The AC is not working either.

So that would mean the AC relay is bad? I checked the fuse above the relay panel and it was fine. I pulled the relay out and a coworker who is an engineer tested it and said it appears good.

So now what? Is it possibly the control head in the dash? I saw some people mentioning that if the freon is low the compressor will not run. Since my "4" does not work and the AC does not work I would think its probably something both have in common like the AC relay. If the AC pressure was low would that preclude the "4" from working?

I am not getting this. I dont think its the resistor on the blower motor because the AC is not working either.

Thanks.

Reply to
John W.
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Interesting tie in with the A/C.

Normally the fan speed control goes through a series of resistors in a resistor pack mounted on the air handler (that helps keep the speed control resistors cool) Normally the resistors are more likely to go than the switch. In some cars the resistors are built into the switch. A failing bearing in the blower motor can cause a high current that can burn out resistors, so if you start having other speeds drop out, then that would be a good indication of a blower problem.

Does you A/C work on other speeds?

Reply to
Joseph Meehan

I don't remember. Are 90's A2 or A3? Anyway, if position 4 on the switch goes through whatever, position 4 on the switch is still a possibility. You may just have another problem with the AC. There's a low pressure cutout on many systems that won't allow the compressor to operate when there's low refrigerant. You might just be low.

On my A3 ('95), the switch needed replaced. You could tell it was going because it was HOT. The plastic over the switch also blistered. I put up a how-to here:

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Hope that helps, Mark '95 Jetta GLS

Reply to
Mark Randol

Thanks for the info.

My 90 is an A2. I have the bentley manual. On Friday with a coworker who is an electrical engineer we tested the switch with a multimeter. There is current coming out of the switch on "4". My coworker things its either the control head or the relay. He doubts its the relay because he tested it but he said it still could be.

We also jumped the low pressure switch to see if we could get it to engage and it would not. This leads me to beleive its definitely the control head or relay. I am going to try to check the control head to see if current is coming out of it.

Thanks.

Reply to
John W.

You may want to check the switch itself with a continuity tester to see if the high speed postion is working. Or drop in a junkyard and buy another switch for 5 dollars or so and switch, no punn intended. The blower area is easy to service also. I just replaced a blower on an A2, 10 dollars in a junkyard I pulled the resister assembly out too on the junk car but did not need it, (I think the donor was a 91 or 92 Jetta, you have to remove the glove compartment, drop the lower tray - and bend out the dash by removing two screws to remove the blower assembly - one on the end of the dash next to the drop and another screw near the middle console that also has to be removed

An interesting thing about this is that the original had a different blower. An 88 A2. The original blower was all metal with a short rubber air-hose coming out of the heating duct to the blower moter metal hole on the side. That original also had foam around the blower moter. I was a bit nervous buying the *different* blower motor replacement but it fit perfectly by having a plastic shrouding around the motor (in leiu of the foam) with a plastic duct molded in that fit over the hole where the original hole in the duct that the rubber hose came from. Different but fit perfect. I had to snip the electrical connector though from the original blower motor and solder to the two, replacement blower moter wires as the harness was different. Works perfect.

(this junkyard has *two* 2.0 Audi 3A engines in Audi junkers but ain't tellin' I may put one in a Rabbit I have laying around - they have no clue at VW parts and pricing )

Harry

Reply to
Harry

Do you have power to the relay? This is a seperate power feed from the first three speeds.

My 88 Jetta when I first got it, did not work in 4. Came to find out the main feed to the relay was disconnected. Once I hooked that back up, the blower worked in all speeds again.

JW

Reply to
cyberzl1

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