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A2 GTI 8V - Odd A/C Problem

With all of the talk about mileage recently, I looked at my numbers and was shocked at how low they seem. I've been getting about 24 town and 27 highway. My engine is in pretty good shape- I'm using Mobil 1 15W50, Redline MT-90, Bosch Platinum 2, and run 89 Octane Fuel. I've installed the windage tray and the oil pump baffle and recently replaced my O2 sensor plus I have a K&N filter. Anyhow, I think I may have found a possible culprit. Here are the scenarios:

Scenario 1: Car is Off Switch vent selector to Vent (either) Turn Car On Result: Air blows at outside temperature. I have also noticed that the A/C will sometimes come on if the engine gets hot (2/3 temp gauge) even with the switch on vent.

Scenario 2: Car is Off Turn Car On Switch vent selector to A/C (any) Air blows at good A/C temperature Switch vent selector to Vent (either) Result: Air still blows at A/C temperature If I switch between Vent and A/C I noticed the engine RPMS change slightly.

A/C appears to remain on. Occasionally it switches off. This problem seems to be worse at highway speeds and better at lower speeds. The A/C should always switch off when put into vent, yes? Any ideas as to why this might be happening? Maybe the A/C control head is going? Any other ideas?

TIA, Craig Smith aka Kaji Shun

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I get ~24mpg in town (a2 8v also). Not sure about the ac vent control problem but I have noticed that mine is sensitive to position and a very slight movement of the arm can bring the ac on.

Reply to
John Rutledge

I have an 88 a2 jetta and the ac compressor disengages exactly when I move the selector to anything else but AC. Not quite sure what you mean by "the up and down positions". If you mean split ventiliation I get it. It could be cold for 30 s due to the fact that the evaporator has not cooled down to the inside temperature of the car. This is quite common in most cars. The easiest check is to have someone check to see whether or not the clutch disengages when you switch from ac to non ac. You'll probably find the clutch disengages right away.

Reply to
Mustangbrad

Oh and btw matt, you should be running 20w50 in that 1.8 of your's , the book calls for it.

Reply to
Mustangbrad

i know what you're saying, but that is difficult to do when travelling at highway speeds (which is when the problem is the worst). when travelling at normal speeds it sometimes happens, but the vent high and low positions still don't act as designed- the a/c is definitely still on. but not all of the times.

in my previous post i also mentioned that if i balance the vent between high and low, the a/c cuts out after about 30 seconds. i checked my mileage over the last two days with doing this and i got 400 miles in one tank for a whopping 31.5 mpg! (that's an incredible improvement over the 26.5 mpg i got with the a/c on at all times.) whohoo! so is my control head just too sensitive?

craig

Reply to
Kaji Shun

True, and I will be switching back to that. I did thinner oil for a while because I felt the engine needed something thinner to clean things out (ticky valves, etc). My next oil change will be 20W50 for sure.

Reply to
Matt B.

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