Anyone convert A/C to R134 by deleting EPR valve?

Classic auto air states that converting to R134a you should remover the EPR valve and ad a themostate. Has anyone done this modification?

I considered it, but did not do it.

Instead i took my old EPR valve apoart, cleaned it, and got it working as it should. Manual says they are not serviceable.

My previous experience with 134-A conversion was a result in capacity loss, so I was less than impressed with conversion results.

My question for Classic Air would be, "Can an old-style RV-2 compressor clutch tolerate the cycling presented by the line t-stat?"

In the original configuration the EPR valve prevented the evaporator pressure from getting too low. This is the purpose of the t-stat Classic Air sells.

EPR valves are no longer available from the dealer in my area, and I have a reliable and knowledgeable MOPAR parts contact.

If you do the 134-A conversion, I hope you are satisfied.

The EPR valve on the Mopars controlled the evap pressure so it would not freeze up the same as Suction Throttle Valves did on Fords and GM cars. I have not seen any of them used since the late 70's and cycle AC systems came out. I would think the evap would freeze up without the EPR valve unless you put some kind of cycle control switch on it. Ron

I did do the Classic auto air conversion to R134a...
I own a 70 Coronet 2 door hardtop with factory A/C.

The EPR is removed and they provide (at a not so cheap cost)
a thermostat to put into the system (external)...

The system works very well overall...
I had them redo every soft line,
pressure test and clean the evaporator and condensor
and they rebuilt the Air compressor removing the EPR and
replacing the oil etc... new clutch and I got a new
dryer (aftermarket) and new expansion valve (also aftermarket)..

Having done this...my recommendation is this:

If you have to have a stock appearance then obviously
rebuild/redo your original pieces...

If you can live with a non-stock look (and I've softened my stance
on this quite a bit, I used to be diehard stock)
then I think the better solution is to move to their compressor
upgrade package. it's lighter, more efficient and cheaper overall...
Granted it will not look stock...but you can install it and
have it look really good (IMHO)...

As far as the performance goes, I can't complain... I can get
36-38 degree discharge air on a pretty hot day... Even my newer
Ford can't do any better than that. It's usually around 40...

The external thermostat is installed per their instructions
I swear I almost never see it shut off... but on really hot days
it may not.... I can't say I've had any real issues with it
other than the thermostat line broke off and I had to replace it
(like $40.00 etc) which pissed me off...

Other than that they did a really nice job with the lines they look
exactly stock... the condenser looked like a brand new piece
as did the evaportator and heater core... I can't complain

Overall with shipping, freon and a couple of their thermostats
it was a little over $1000.00...

There is a gasket/insulation rebuild kit you can get for the
factory A/C box...it's absolutely worth the money...
But it's time consuming to disassemble/ clean/ refinish / and rebuild
that box....

Factory A/C cars can easily add $1000.00 and about 40 hours or
so to a restoration....If any of you have done it, I'm sure you
know by now that the 68-70 B-Body A/C box is a PITA to install by yourself!....


NOTE:

One of the problems I experienced with this overhaul/restoration was "expectations"...
I guess having spent a fortune on it I expected it to blow me out of the car....
We'll it didn't, but it's not because of the discharge air...
It's because the original factory blower motor circuit is by design LAME...
and my restoration even included and NOS blower motor!

As I learned from MAD Electrical...
All the voltage that goes to the blower motor, first goes through the fan switch...
then to a 3 step resistor and then to the blower motor...
So the voltage at the motor when running is not 12.6 volts.
It's more like 10.5. So your blower motor output vs a new car is very lame in comparison...

That has nothing to do with Classic Auto Air's rebuild.

You can bypass the MAX A/C full speed blower motor with a relay fairly easily.
But for the low/med setting, you're pretty much stuck with the
factory design...

I'm going to go the relay for the max setting but I have not done that yet...
I have done the alternator bypass and headlight relays from MAD
Electrical and they are EXCELLENT upgrades...
I also installed a relay for the A/C Compressor... from MAD...
Again an excellent upgrade...

That's all the news fit to print!

Best of luck to you either way...

EPR should be removed and a thermostatic cycling switch installed.

That being said, RV2 compressors really weren't designed to have their clutch cycled.

Installing a Sanden-type compressor is really the best way to go.

On my 70 Sport Satellite, I got Classic Air to redo my lines and provide a new evaporator and heater core. I used a local shop to vacuum test and then fill the system. I asked them about the EPR valve, and they said, no, it should be ok. After getting the car back from them, on some of the hottest days we had (close to 35deg C = 90deg F), the system worked flawlessly - freezer cold !!!

As was posted before, a B body ac/heater unit takes a lot to rebuild and get back into the car. It was much easier to install, while the complete dash was out of the car !!! . . . pretty much figure I have 50 hours in that unit under the dash !!! . . .

Good luck with your car . . .

Cheers,

Mark

Quote:

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EPR should be removed and a thermostatic cycling switch installed.

That being said, RV2 compressors really weren't designed to have their clutch cycled.

Installing a Sanden-type compressor is really the best way to go.

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A cycling AC thermo clutch switch....that makes sense without the EPR valve.
I agree about the old Mopar RV2 comp as it takes a small V/8 to run the thing. They would really drag the idle down on my old 318 Scamp as it had no idle solenoid on that model and they would not help the gas milage. Newer style comp much better. Ron