aklim

I have R134A because the PO did it. Now that I replaced everything but the condenser and it is set up for R134A, we have a question. What switches? The high pressure and fan are safety switches in case the pressure gets too high.

So the low side switch sits on the pipe COMING from the evaporator core. NAPA had the fan switch and I am getting the high pressure switch from White Bros Racing. Case closed, I think

Autozone has a low pressure switch that works regardless of R12 or R134A

Apparently NAPAONLINE has 2 options:

http://www.napaonline.com/Catalog/Ca...434_0120054090

http://www.napaonline.com/Catalog/Ca...883_0120054092

The mechanic says they are the same. So the fact that there is R134A specific means nothing? Any reason why I should toss a good sensor out for that one? TIA

hooked073

just for my own information what year? i may need to ask you something if mine is the same yr. You defently 100% need to change the low pressure switch. In fact this is the only switch I have ever needed to replace doing a converson and I have done tons. you a/c will cycle to offen without replacing it and you will not cool. Your mechanic is dead wrong saying the 2 are the same. On some cars I have had to use an adj low pressure swith to get thing right but 98% of the time a 134 switch will work fine

gerardvg

Hi

Follow the small pipe it will have two pressure switched on it close together, one round pressure switch with a round electrical connector. That is to request the cooling fan and is connected to the ecm, if you are running the engine the cooling fan will come on if the small round plug is removed.

The other pressure connector is the high pressure safety, it has two small spade terminals that will cut power to the a/c clutch.

Keep the standard pressure switches, they won't be bothered by R134A

aklim

Sorry, 91 corvette. Standard. NOT ZR1.

aklim

What is your opinion on whether to use the R12 or R134A Low Pressure Switch? The other two are standard and don't change. There are 2 offerings in Low Pressure Switch from NAPA.

WW7

aklim,
Email " SunCr " , he's the resident expert on the C4 A/C units..He helped me a few times with my A/C problems.......WW

http://forums.corvetteforum.com/memb...534-suncr.html
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gerardvg

Hi again.

I am using the original pressure switches, have converted to R134A more than 6 years ago and still blowing cold air.

The only change i made is throwing the old 85 rubber a/c hoses out, got some new barrier hoses made. You should be fine with the 1991 as they should already have the newer barrier hoses since car manufacturer's started using R134A in the early 90's.

WVZR-1

If you're referring to the "cycling switch" at the evaporator I believe the correct '91 application is likely adjustable. A visible check would confirm. I recall sometime ago "SunCR" mentioned that most "off the shelf" regardless of application seem to be set for R134a pressures.

Deepa

I just replaced mine with the 134a one from napa. I do not know what was on there to begin with but the plastic mount cracked. No issues with the 134a spec one.

Mike

scotth48

Having to make a decision on my '93 concerning switches. So the low pressure switch is what I should change? So a switch from a '94-96 will work?

I also have a new accumulator which is for R12 and looks like it may be used only in the '93.i thought I could use one for a '94-96 model but they don't seem to have a R134 inlet like my R12 one, so will just go with the adapter for it.

aklim

I have to replace the low pressure switch since it is leaking

sledge_78

Aklim,

In your replacement of parts that come in contact with the refrigerant. Keep in mind that R-134A is corrosive, R-12 is not. So, if you are replacing parts that come in contact with the refrigerant and you intend to use R-134A then I would select those replacement parts that are R-134A compatible.

Sledge_78

aklim

The high pressure and fan switch do not have this option. Only the low pressure switch does. I thought it was for better pressure control since 134A is different?

WVZR-1

I see R134A advertised like this "ALWAYS" I don't believe I've ever seen it mentioned before that it's corrosive. Did you intend to mention maybe something else?

An excerpt from most anywhere should read like this:

R134a is also known as Tetrafluoroethane (CF3CH2F) from the family of HFC refrigerant. With the discovery of the damaging effect of CFCs and HCFCs refrigerants to the ozone layer, the HFC family of refrigerant has been widely used as their replacement.

It is now being used as a replacement for R-12 CFC refrigerant in the area of centrifugal, rotary screw, scroll and reciprocating compresssors. It is safe for normal handling as it is non-toxic, non-flammable and non-corrosive.