Newly converted R12 to 134a system

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Donald
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Newly converted R12 to 134a system

Postby Donald » Tue Jul 11, 2017 1:14 pm

Hi All,
I just converted my 92 Miata to 134a from R12. I replaced the compressor and drier but not the expansion valve. I didnt go the valve yet because it is very hard to get too. I evacuated the system and it does not appear to leak. I used ester oil in the compressor and drier. I installed 22 oz of 134 and the system cools somewhat but does not get cold. The refrigerant seems to be circulating but the clutch does not cycle it runs all the time. When I got about 20 oz in the system the froth in the sight glass went away and there are no bubbles now but still no real cold air. Do you suspect a bad expansion valve? low side pressure is 30 and I havent read the high side. It is 94 degrees here today.

Any suggestions would be appreciated.

Thanks,

Don
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Tim
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Re: Newly converted R12 to 134a system

Postby Tim » Tue Jul 11, 2017 11:42 pm

Get low and high side readings.
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Donald
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Re: Newly converted R12 to 134a system

Postby Donald » Mon Jul 17, 2017 4:35 pm

I am back with some info for TiM. I took the time to finish the project by replacing the expansion valve and most of the O rings. I evacuated the system, still no leaks but I now have high and low reading.

Aprox 20 oz in the system, no cold air but not ambient. warm day about 82 degrees. The system capacity, with 134, should 23 oz.

High side pressure is 125 and the low side pressure is 120. I need some suggestions.

I want to thank TIM for responding to my first post.

Thanks

Don
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Tim
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Re: Newly converted R12 to 134a system

Postby Tim » Mon Jul 17, 2017 9:18 pm

High side pressure is 125 and the low side pressure is 120. I need some suggestions.

Means the compressor is not working. Clutch engaged?
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Re: Newly converted R12 to 134a system

Postby Donald » Tue Jul 18, 2017 3:36 am

OK , but why is the low side so high when the system only has 20 oz (undercharged)
Donald
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Re: Newly converted R12 to 134a system

Postby Donald » Tue Jul 18, 2017 4:09 am

Sorry, yes the clutch is engaged and is running continuously. 134 seems to be circulating as I can see the foam in the sight glass.
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Tim
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Re: Newly converted R12 to 134a system

Postby Tim » Tue Jul 18, 2017 7:31 am

Bad compressor.
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Donald
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Re: Newly converted R12 to 134a system

Postby Donald » Tue Jul 18, 2017 12:58 pm

Hi Tim

Thanks, I get the bad compressor part. With 120 lbs or whatever the 120 means , indicate that the system is overcharged ? If so how can it be overcharged with 20 oz. of refrigerant? Just wondering.

I will get another compressor and try again.

Thanks for all your help.

Cheers,

Don
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Tim
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Re: Newly converted R12 to 134a system

Postby Tim » Tue Jul 18, 2017 1:08 pm

Because all you have is static pressure. If it were over charged, you high would be 400/500. Not 120!

Pump is not pumping.
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Re: Newly converted R12 to 134a system

Postby Donald » Wed Jul 19, 2017 4:33 am

Hi Tim,

Got that. New pump is on the way.

Thanks again.

Don

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