Where there manual A/C along with ATC

[Clover]

For what it’s worth: ‘71-‘73 Auto Temp II is pretty easy to work on and upgraded parts are available from Performance Analysis Inc. I am running a regular EPR valve and it works fine (I don’t use the car during the winter). Also, I don’t think that there are non-ATC ‘72-‘73 Imperials.

 

[Clover]

Performance Analysis Co.

 

[Davea Lux]

Yeah I see it now. For auto temp systems one section of the manual refers to an ETR valve at the evaporator and another section of the manual refers to an "ETR" valve at the compressor (non-auto temp systems refer to only an "EPR" valve in the compressor). The manual also describes testing the ETR valve (the one in the compressor) by applying 12 volts to it - which makes me think that while both the EPR and the ETR control suction pressure, they do so in somewhat different ways.

So revisiting my original questions about the "thermal wax" (post 23), how does the EPR valve (in the compressor) operate? Is it strictly controlled based on pressure or is there a thermal component (thermal wax)? Is there any way to test the EPR valve out of the system?

Thanks and sorry for any confusion i may have created.

If you remove the suction line and you can see the capillary sticking out the end of the valve, it is the thermally controlled wax valve. These were considered an expendable item and I do not know of any test procedure except with the unit installed as specified in the FSM. The inner section on this type valve is pushed down to open the ports, if it is closed a room temp, it is probably dead.

Dave

 

[DeMopuar]

For what it’s worth: ‘71-‘73 Auto Temp II is pretty easy to work on and upgraded parts are available from Performance Analysis Inc. I am running a regular EPR valve and it works fine (I don’t use the car during the winter). Also, I don’t think that there are non-ATC ‘72-‘73 Imperials.

I own a 1972 Imperial coupe that I need to restore with the H51 regular A/C fender tag code on it - so at least this one has regular A/C - I have yet to see another Imperial without ATC II that is from 1972 or 1973. True story............

 

[Clover]

Wow, that’s really cool! You should post a pic of the tag on Doc’s tag thread. It’s good to know they made some without ATC. Supposedly, they also were made without a/c, like Matt’s silver sixty-seven (very alliterative!)

 

[DeMopuar]

Here's the fender tag from my 1972 Imperial coupe with manual A/C. It was assembled in December of 1971, so it wasn't necessarily an early build - and I've never seen another 72 or 73 Imperial with factory manual A/C. Definitely says H51 for regular manual A/C.

 

[Davea Lux]

Here's the fender tag from my 1972 Imperial coupe with manual A/C. It was assembled in December of 1971, so it wasn't necessarily an early build - and I've never seen another 72 or 73 Imperial with factory manual A/C. Definitely says H51 for regular manual A/C.

View attachment 197705

Probably a Chrysler employee who knew what they were doing decided to save a preferred customer a lot of trouble by ordering the car without ATC II.

Dave

 

[Clover]

Thanks for posting the pic. That is rare! I think that Dave is likely correct.

 

[ayilar]

Here's the fender tag from my 1972 Imperial coupe with manual A/C (...) I've never seen another 72 or 73 Imperial with factory manual A/C. Definitely says H51 for regular manual A/C.

Thanks for posting the pic. That is rare!

Here is another. That car was for sale in the Chicago area this past spring.

 

[70bigblockdodge]

If you convert to 134 and don't drive the car in cold weather just eliminate the ERP and let the TXV do it's thing. 134 runs at higher pressure across the board. If you are not running the system at low temps, i.e. fair weather driving, it will not come into play.