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Older TEV system How does it cycle?

vdubspeed on Sat April 19, 2008 10:33 AM User is offlineView users profile

Year: 1979
Make: VW
Model: Rabbit C
Engine Size: 1.8 16V
Refrigerant Type: R134
Ambient Temp: n/a
Pressure Low: n/a
Pressure High: n/a
Country of Origin: United States

I've upgrade my Rabbit's A/C system from an old York compressor to a Sanden compressor. The results were weak so I figured I would do a system overhaul. Last night I ordered a boat load of parts from

What I'm curious about though is the compressor cycling. The only wire that goes to my compressor is the 12V when the a/c is turned on. I don't believe it came factory with a cycling feature. I know for sure there are no HPCO switch or anything.

Does a Sanden 508 have a cycling feature built in or is installing an aftermarket HPCO switch "mandatory"

Also...if I do have to wire it in...does it just go to ground on one spade connector and the other side go to the ground for the compressor?

Thanks for your expertise,



Spector on Sat April 19, 2008 11:43 AM User is offline

If I remember right the older vw systems did use an expansion valve they had a thermostatic switch on the evap to keep the system from freezing up that would cause the system to cycle just like a clutch cycling switch does on an ot system it is in line with the power lead to the compressor.
that system should have a low pressure cutout switch to prevent damage to the compressor in the event of a low charge.
as far as a high pressure cutout it may or may not be present some low and high pressure cutouts were combination switches and were actually one unit.
if your system does not have a high pressure cutout and you are using any refrigerant other than R12 you are actually required by law to install one.
I wish I could tell you which one yours is but the only reference material I have on VW goes back to 84.

hope this helps.

Edited: Sat April 19, 2008 at 11:58 AM by Spector

vdubspeed on Sat April 19, 2008 12:18 PM User is offlineView users profile

thank you kindly sir.

It does have a little coil wire that attaches to one of the a/c lines but I didn't know what it was for.

As for your information about 84's...that would be nice to know what it says because my 79 system is identical to 84 GTI(except I've upgrade the compressor)

Thanks again,



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