Automotive Air Conditioning Information Forum

Hello all - Working on a 1980 Volvo 265 (Which is a rare factory 6 cylinder version of the popular 245 model). However, the car now has a Chevrolet 4.3 V6 in it. I have the air working, sort of, but its with the old Volvo AC wiring which has no safety switches at all (not low pressure or high pressure!). It also has a crappy thermostatic switch with a capillary tube on it that is not working very well (kinda stiff to turn) and isn't cheap to replace, if and when you find one.... I would like to use all the GM stuff (low pressure switch, high pressure switch (which is built into the rear of the AC compressor anyways) and the cycling switch, and do away with the thermostatic switch inside.

Does this sound doable? Doesnt the cycle switch replace the thermostatic switch? Also, where should I be locating these switches? One of them is on the drier for the chevy - and that I think is the cycling switch, but the drier on the volvo is not mounted directly to the evaporator core like it is on the chevy. So I am not sure about it.

Also, will the cycle switch work with the TXV system? The GM used an orifice tube...

This should get me started.

Thanks in advance...

Anything at all guys?? AC is working right now,with 50 degree vent temps when its 85+ out, but I am worried that it wont be working for long. I am starting to think that this HT6 compressor does not like (not compatible with??) the expansion valve type system...It has tripped the high pressure relief valve a couple times....just kinda randomly....

A lot depends on the system components - are you trying to use the OEM Volvo condenser?

The GM CCOT system would mean changing to an accumulator after the evaporator at least.

If you are seeing HPCO activity, you will need to get us some pressure readings & temps to help you. High / Low / Ambient / Vent - both at idle & 2,000 engine rpm

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I have a black can (drier) located in the small line between the condenser and the evaporator. Are there universal accumulators that I can install? Is the TXV causing a problem with the HT6 compressor, since it can slow or possibly stop the flow of refrigerant? (where as an orifice tube i assume has a fixed orifice allowing a fixed amount of refrigerant to flow at all times)

The condenser is a universal aluminum parallel flow unit, a little bigger than the OEM tube and fin condenser was. Low side pressures were approximately 30-35 psi with a high side of about 175. ambient temp 80 to 85 and vent temps seem to vary from 50 to 60 degrees. I think it should be colder, but IDK. I am running an electric fan (from a Ford Taurus, a 2 speed fan, I have the low speed wired up to come on with the AC). I put some material around the top/bottom/sides of the condenser, so that all the air has to be pulled through the condenser and cannot go around it instead.

Id like to get rid of the thermal switch in the dash as well as the relay that is in there also (ill move the relay under the hood), All that crap adds alot of extra wiring up under there which it has far too much of already.

The thermostatic switch is there to keep it from icing the evaporator. Really no need to change to CCOT operation.

The thermostatic switch could be relocated, as long as it senses the evaporator temp to keep it from developing ice.

This is a common replacement switch:
http://www.truckerac.com/thermostatic-s ... 04075.html

I would contact the site sponsor http://www.ackits.com/ & see if they can supply that part at a better price - they usually can.

Still need some 2,000 engine rpm pressures & temps to help you with the diagnostics.

bohica2xo wrote:The thermostatic switch is there to keep it from icing the evaporator. Really no need to change to CCOT operation.

The thermostatic switch could be relocated, as long as it senses the evaporator temp to keep it from developing ice.

This is a common replacement switch:
http://www.truckerac.com/thermostatic-s ... 04075.html

I would contact the site sponsor http://www.ackits.com/ & see if they can supply that part at a better price - they usually can.

Still need some 2,000 engine rpm pressures & temps to help you with the diagnostics.

I have one of those switches somewhere. I bought it for this car, because I broke the original one. But once I saw that it was very different from the one the car had, I decided not to use it. Unfortunately I no longer know where it went, so unless I can find it I will buy another one (from the site sponsor of course!) the original one looks similar to that one, except it has an on/off switch built into it. If you turn the switch counterclockwise all the way, it turn the AC off. and I assume that the further you turn the switch clockwise. the colder it will allow the AC to get. I have not been turning mine up more that 1/3rd of the way because Ive had issues (in the past, before I upgraded to the electric fan) with the presssure getting too high and it blowing out a significant amount of refrigerant & oil.

The AC does seem to be working OK. The car has unfortunately broken down yesterday afternoon (no spark for some reason) so until I get it running, all I have are the idle speed readings. However, I have done that 2000 rpm test previously as that is when the pressure had been spiking super high in the past - however this time it didnt seem to make a whole lot of difference 30-35 to 175-180 at around 85 degrees.

How should I wire in the GM switches? Do I need the cycling switch if I use the dash switch? Doesnt it basically do the same thing (in a different manner)? The high side switch is in the back of the compressor I believe and the low side I am not sure about. The cycling switch is on the drier on the GM, it may take the place of the low side switch, i dont really know.

The cycling switch serves the same purpose as the thermostatic switch - it prevents icing of the evaporator. You need one or the other, not both.

If you have a high pressure cutoff switch (HPCO) it should be used as well.

Your post is not clear - was the High Pressure Relief Valve opening & venting refrigerant when you saw the spikes? If so you no longer have a full charge, and many of those valve fail to full reseal after activation...

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