Ac issue after blower switch fix 86

[yama1]

I have an 86 coupe 911 with an ac issue. Ac was fine when blower was working on low and med. The high speed didn't function. So the first thing I do is check the fan speed switch. The high side was corroded, so great an easy fix. I cleaned and made new wire and reinstalled. The blower now works on all speeds, but now no cooling. Is this just a fluke or did temp control switch or resistor pack get damaged? Any suggestions

[Barrpete]

Check to make sure you didn't damage the capillary tube on the temperature switch when disassambling the console. That could cause your problem.

[yama1]

I will check the tube again. I hope it's not that sensitive. The tube wire seemed pretty flexible, but could have got kinked. Is there any way to check this without replacing it arbitrarily? Would the resistor pack have any effect? Thanks for the info. I am out of town now, but will check into on my return.

Thanks

[Barrpete]

You can check the temp switch by jumping the two wires that attach to it & bypass the switch. If the compressor kicks on then your switch isn't working.

It could just be dirty though. So if the AC works with the switch bypassed, then you can remove it and dip the capillary tube in ice water. If you can see the contacts open & close inside the switch you can probably just clean them up with contact cleaner.

Check the voltage at the compressor, when I had a similar problem last year I was getting about 7 volts and it turned out to be dirty contacts in that switch. Cleaned them up & working fine ever since.

By the way an original size temp switch is NLA so you have to cut/modify the console switch housing to make a replacement fit.

If the resistor pack was bad I don't think your fan would work at all - but I could be wrong.

[yama1]

Tried jumping - no AC engagement. I think maybe something is loose. Drove up the street a bit and noticed some amount of cooling with temp switch mid-way. I then adjusted to coldest setting and nomore cooling.

Need to get the wiring diagram and check each component. Is worth changing the switch out to a newer one even if clutch does not engage when switch is bypassed?

[Tigerrat]

As mentioned, see what is happening at the compressor. Clutch engaged or not? Voltage to it? Should see a change while turning temp control. Can always rig 12 v to it to see if you get cooling and then back track electrical problem from there. Ken

[Barrpete]

Originally Posted by yama1

Is worth changing the switch out to a newer one even if clutch does not engage when switch is bypassed?

Probably not. If you've bypassed the switch and its still not working the switch is not the problem. Besides you will have to modify the plastic console to make a new switch fit since the original size is NLA.

The problem could be with the clutch itself. If you have 12V at the comrpessor wire make sure the clutch is actually engaging.

Griffith's has a great troubleshooting guide on their web page.

http://www.griffiths.com/achelp/

[yama1]

Cool, I will check griffiths website for more detail.

just diagnosis info. Well drove around today for a bit and am thinking of the following now:

1. The AC will cool on the low speed setting - triple checked this
2. No cooling on med and high. I would not think the blower speed connection would have anything to do with this, but... remember the low and med side worked before cleaning the blower switch and reconnecting. Could be high & low terminals are switched, but that doesn't make sense. No sure what role the resistor pack plays for med and high in the ac system.

I also noticed the previous owner changed to 134A and installed a different relay in the back so that could be some of the original issue that I only noticed when examining the faulty high position.

[kuehl]

The right hand knob, ac evap blower has to be in any of the three fan speeds for the ac to work. The left hand knob, thermostat, is at max when turned fully clockwise. If you are getting air out of the vent on speeds med and high however it does not feel cool, park the car, leave the engine and ac running (thermostat at max, fan speed med or high), open the engine trunk, look at the compressor clutch, if the outer hub (closest to the rear bumper) is turn along with the belt pulley then your clutch is engaged. There could be several issues for warmer air however the most likely suspect is low refrigerant charge.

The shunt resistor pack controls the three fan speeds and has a mechanical (thermo) contact to turn off the fan in the vent the motor draws too many amps; but it does not work all the time.

You have to clarify your statement on "No cooling on med and high", do you mean no vent air or no cool vented air.

Where is this relay located in the back?

Originally Posted by yama1

Cool, I will check griffiths website for more detail.

just diagnosis info. Well drove around today for a bit and am thinking of the following now:

1. The AC will cool on the low speed setting - triple checked this
2. No cooling on med and high. I would not think the blower speed connection would have anything to do with this, but... remember the low and med side worked before cleaning the blower switch and reconnecting. Could be high & low terminals are switched, but that doesn't make sense. No sure what role the resistor pack plays for med and high in the ac system.

I also noticed the previous owner changed to 134A and installed a different relay in the back so that could be some of the original issue that I only noticed when examining the faulty high position.

[yama1]

Well after a little bit more investigating.

I found that the clutch would only operate on Low. With the switch position in Med or High only air and no clutch engagement.

Well turns out that the previous owner is using a different switch which was part of the original problem with no high speed blower in the first place. I assumed that it was stock - my bad.

I will buy new oem switch in the morning and hopefully that will solve my issue with the med and high. If switch does not solve, i will continue the wire diagnosis

The previous owner installed a relay in the back right above the original relay location which is not there. There seems to be some other wires not connected either.
The P.O. added a switch to control the evap fan (left side black housing) so that the 134A conversion could operate with or without the clutch engaged.

The relay has only 3 wires leads which seems odd - connections as as follows;
red to fuse - 10-12 gauge brown wire(possibly back up front in main harness or to ground) - and 1 wire going to compressor Y.

I disconnected this lead and there is no loss of function that I am aware of. Original thought was that the pass side original yellow wire feed to the clutch was disconnected or damaged from P.O.

So to me I can't yet determine why the relay was installed or even needed unless they were trying to bypass a wiring problem in the original relay or circuit.

Thanks for the input, I'll post some pics and well see what tomorrow brings