I will be converting my daughters AC to R134 this weekend using the Volvo kit. Seems that it is always a challenge to know the correct amount of R134 to put in.
Some say you must weigh it.
Others say it is done by watching low side pressure.
Still others say add until it cools well.

Curious why no one says to use the sight glass as a guide. Why can't we fill on a hot day, doors open, fan on full, RPM 1500 or so until bubbles just stop. Of course watching pressure and performance at the same time.
Thats what I have done always with R12 filling.

Does the sight glass have any relevence with R134?
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David Hunter

Hello,

As Jim said, you need to have the correct amount fo pressure in there or you will overfill and blow out a line.

That's the first of 3 issues I can see.

The second is that you will have to evacuate the system of any trace of R12 and it's lubricant. Any trace of this will react with the new 134a refrigerant and destroy your compressor. The shop that did mine went as far as flushing out the system and evacing twice before introducing the R134a.

The third is I am wondering why you are converting it. If it's because the system is no longer functioning, then you have a bigger problem than just conversion. There is a leak somewhere and it needs to be fixed. If you have the detection equipment, then all the power to you. If not, you'll get a few hours out of and and *poof* it doesn't work and you have wasted 30 bucks of refrigerant.

Otherwise, go for it!!!

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Happy Bricking!!! - Richard - '87 245 DL , '82 242 GLT - Half a million km between them!!!

Thanks for your response.
Oh yes I plan to pull the compressor and drain oil, then flush the system and pull a vacume, been there done that before.

Reason for the conversion is that I have a leak on the LP line to compressor. I am replacing this line. Do not wish to pay the price for R12 and risk discovering another leak. Been there done that too. Also a have an almost full 30lb canister of r134 so I don't really care if there is a newly discovered leak.

I am not an environmentalist whacko misguided nuthead and now know that this R12/ozone layer over Antartica stuff is a non issue anyway.

Just wondering about value of using the sight glass during charging process.
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David Hunter

134a always has bubbles; you'll overfill
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Jim McDonald

Thanks, I guess that is what I thought but was curious why the official approved, expensive Volvo conversion kit has a receiver/dryer with a sight glass on the top.

So you do see bubbles under all conditions even with lower ambiant temps?
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David Hunter