A/C not working

[doug_porsche]

Hoping that the brain trust can find the hole in my logic, and save me from taking my dash apart.

When I push the fan control to turn on the air conditioner, nothing happens. No light, no compressor, no change at all.

I don’t think its fuse 11 or 12 because the interior fan works
I don’t think it’s the ground because the interior fan works
I don’t think it’s the thermostat, trinary switch or relay RR01 because the AC light does not come on.
I fear it’s the switch itself, or the plug to the switch.

The way I am reading the Heating ventilation air conditioning circuit, if fuse 11 and/or 12 is good and the ac switch is working, and the ground point is good, I should have a light at minimum.

Hope there is something I am overlooking.
Any Ideas?



as Jeff said on removing the dash

Quote Originally Posted by NobleM400 View Post
All you need is 3 foot long, triple-jointed arms, eyes and lights embedded in your hands, and more patience than anybody I know. Jeff

Search tags ac a/c air conditioner conditioning con

[Adrian W]

if you cant here the clutch coming in my money would be the relay, second choice would be the switch, I am assuming the fan function works,

the base is made up of 1/4 receptacle's (its cheap) they corrode easily, you may wish to pull all of the relays and un the engine bay and give them a good clean, try switchclean, you should be able to get it a maplin.

Edited by Adrian W on Wednesday 11th May 08:03

[TuxMan]

another vote for the relay in the foot well .

[Green3R]

Hi,

given your analysis, yes you should have a light as a minimum.
So, switch, wiring to switch.

A quick test without removing the dash-
Leave the switch off, find the thermostat/trinary switch. Put 12v in there- assuming the thermostat is closed at ambient (and working) you should get the light on.
I'm not sure how the trinary switch operates, but assume it's normally closed and therefore the ac relay should also click on.

[doug_porsche]

I will check the relays in the foot well.

I had been avoiding this path as my step one was just trying to get the light on the fan switch to work.
According to my schematic (US Build manual, Section 8, page 15) power comes in via fuses 11 & 12, goes to the HVAC dash switch.

The AC switch has an output, pin 6, that is tied to the input, pin 5, that goes though the lamp and then out pin 31 to ground.

I have verified that the ground side of this circuit is good (the lamp socket to ground).
I have verified that the lamp is good
I was going to start working backwards and testing the voltage but...
Then I dropped the spring (approx 1.5 mm OD and 20 mm long) that goes between the switch and the back of the bulb into the dash. (new one ordered (i hope I am guessing the size correctly)).

I think to kill time while waiting for the spring, I will:

check the pressure of the A/C system
check the relays in the passenger foot compartment
work on taking the dash apart. (I have read a thread on nobleforums.com where somebody replaced the studs and nuts arrangement with something that makes future removal much simpler.)

Thanks for the input!

[Green3R]

I fitted the heater controls to a metal plate and bonded that to the inside of the dash. Then made some fixings for the dash cover that means I can just push it into place.

I'll find the pics/thread and post a link to it here when I find it

[doug_porsche]

Update. Seems the switch is bad.

The A/C works if I turn the switch clockwise for fresh air.
The A/C does not work if I turn it anti-clockwise for rec.

I admit I am in the habit of only using the air with the recalculation side.

Ordered a new switch off Ebay UK, part number 6422008

Green3r, would love to see your link of the dash if you have time.

Thanks
Doug

[Green3R]

Hid Doug,

here's a link to the dash thread
http://www.pistonheads.com/gassing/topic.asp?h=1&a...

see also
http://www.pistonheads.com/gassing/topic.asp?t=141...
for the continuation.

Edited by Green3R on Monday 23 May 08:28

[doug_porsche]

thanks!

[kenloen]

just fixed my A/C. took it for a re-gas and was told although the pressures are good, the condenser clutch wasn't moving. Turned out it was the relay in the engine bay, usual oxidisation on the pins, replaced and I've got cold air..

[dave sutton]

kenloen said:

just fixed my A/C. took it for a re-gas and was told although the pressures are good, the condenser clutch wasn't moving. Turned out it was the relay in the engine bay, usual oxidisation on the pins, replaced and I've got cold air..

I have the same problem, which relay is it in the engine bay?

[kenloen]

AC relay was the end one, nearest middle of car. my relays have been moved from just under the rear screen to just above the battery.

[dave sutton]

kenloen said:

AC relay was the end one, nearest middle of car. my relays have been moved from just under the rear screen to just above the battery.

Thanks, I have a row of three under the screen but wasn't sure if the a/c relay was there or lower down. Just need to find the time now.