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Post by Charlie on May 23, 2020 17:05:22 GMT -5
for more, here: www.imperialclub.com/Repair/Lit/Master/295/cover.htmalthought there makes mention to a thermal switch for temperature sensing for compact cars ( maybe that's why you had it on your Duster ) I stil have never seen ever that stuff on any 71/74 B body at least. Is not on wiring diagrams or anywhere. on the INTERMEDIATE cars sections, talks about the EPR valve which is the one I talk Yes, this was very helpful in clearing things up for me. So my old Duster would indeed cycle on and off.
If I purchase a new/rebuilt RV2 compressor, then the regulator valve in the compressor should be design for 134a?
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Post by 71se3834v on May 23, 2020 22:17:52 GMT -5
A question and some info.
What is the switch that's located in the receiver/dryer? Pressure switch to stop to clutch if you lose freon pressure? The wire runs from the bulkhead through this and onto the clutch. I should know this since I replaced all the lines, dryer, etc when I got mine up and running a few years ago. I know when I jumped the wires to see if the clutch would kick on it did.
Now the info. Nacho hit on it saying the water temp control valve controls air temp. This is partially correct at least on the '71. There is a blend door that opens when you turn the temp up and blows air across the heater core which is now warm because the water valve opened. Everything is vacuum controlled.
After I charged my system it was still blowing warm. Couldn't understand why until I read the FSM and understood how it worked. I then found that my blend door was stuck. Freed it up (just stuck from sitting idle for 20 years) and it started blowing cool but not cold. Pinched close a heater hose and instant cold! The valve was passing coolant. Drove it with a clamp on it until a replacement valve was bought and installed. 😁😎
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Post by Charlie on May 23, 2020 22:45:07 GMT -5
A question and some info. What is the switch that's located in the receiver/dryer? Pressure switch to stop to clutch if you lose freon pressure? Yes... you are correct. Low pressure switch. |
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Post by Nacho-RT74 on May 24, 2020 1:30:31 GMT -5
I don't know if the regulator is adjustable or can be replaced by a diff one, but per the magazine article about the R12 to R134 conversion I posted they say remove it and install a temp sensor switch. I made the conversion but never installed the switch
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Post by Charlie on May 24, 2020 2:23:39 GMT -5
I don't know if the regulator is adjustable or can be replaced by a diff one, but per the magazine article about the R12 to R134 conversion I posted they say remove it and install a temp sensor switch. I made the conversion but never installed the switch
I'm pretty sure it's not something you can adjust. BUT, if the regulator comes installed in a new RV2 compressor from the local parts house, it would seem it would be for 134a... not R12. Maybe further digging around will reveal this.
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Post by Charlie on May 24, 2020 2:43:30 GMT -5
This is very interesting! I could possibly be dealing with the same thing! The water valve was leaking just a little in my car, and I changed it a few months ago. I installed an NOS Four Seasons valve to correct the leak. I haven't really used the AC since then... maybe just once or twice... but it never occurred to me that hot water could be getting past the valve and causing this AC problem.
I do recall this... it always seemed that the AC blew just a little bit cooler during the first 30 minutes of driving. So that could be an indicator of water getting by the valve. I can also check for blend door operation... perhaps mine, too, is not traveling the full distance it should.
Seems my AC struggles to get down to 60 degrees. I MIGHT have made it down to 57 or 56 at the vents at night. Pressures on the gauges usually look pretty good, and I know the low side hose seems to get pretty damn cold and sweats it's off under the hood... so I have wondered why I couldn't get it any colder out the vents. So if a blend door or heater control valve is acting up just a little, it would explain a lot!!
Currently, I am on board ship and won't be home till next month... but this gives me LOTS to think about before I get home! Thanks for the insight and that share of the blend door/valve experience!
Even if that turns out to be my problem, I still might change out that compressor... just on the grounds that's it's 50 years old and a new one would likely be an improvement. I had been thinking about going Sanden to reduce vibration and use less HP, but if I discover that a replacement RV2 comes with a regulator designed for 134a, I will stick with RV2. I cannot imagine someone selling a new compressor with an R12 regulator... just doesn't make sense.
Thanks for all the knowledge!
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Post by Nacho-RT74 on May 24, 2020 7:30:36 GMT -5
If you find a compressor with the EPR valve for R134 let me know. Maybe the dealer could offer the valve alone ? I'm interested on get the EPR valve back for R134. I really hate get an external temp switch for my car. What I would add is an RPM and throttle switch to cut the power to clutch ( already in hands ) when giving gas or at high RPMs Classic auto air confirms EPR valve is not adjustable, but they don't mention either another option diff than the thermal switch www.classicautoair.com/removing-epr-valves-when-converting-your-mopar-to-134a/But is from 2012 |
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Post by Nacho-RT74 on May 24, 2020 7:44:44 GMT -5
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Post by odzking on May 24, 2020 8:26:36 GMT -5
Not that this will help with your question, but my experience. Back when I restored my 73, I purchased a Classic Auto Air under hood kit. My 73 had factory air but most of it was removed so for lack of time and money I decided to go with the newer system. It has NEVER worked right - EVER!
I have the thermal switch, doesn't do s**t, it still freezes if I run it too long and I've tried moving it, getting another, everything.
My solution: I have slowly gathered all the original parts and will reinstall them as soon as I have the $$ and them restored. IMHO, it is the ONLY way to make this work properly with out freezing up.
Just my 2 cents.
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DynoDave
CO-ADMINISTRATOR
Motown Mopar-Wizard
Posts: 11,169
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Post by DynoDave on May 24, 2020 10:48:06 GMT -5
Good find Nacho. It does say the A bodies had a cycling system. I never knew that.  |
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