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'68 AC Vacuum and Charge Procedure

 
Old 05-14-2019, 10:44 PM
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mrl522
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Default '68 AC Vacuum and Charge Procedure

Hi Everyone - I am in the early stages of troubleshooting the AC on my '68. The compressor runs, has oil and the blower is working but it doesn't blow cold, the system still runs on R12. My plan was to vacuum test it and assuming it holds vacuum (big if), charge it. My question is on the proper procedure. There are two fittings on the back of the compressor (looks like low side is closest to the block, and high side is on the firewall side). There also appears to be a low side fitting at the POA valve. Should the vacuum test + charge be performed with the high side connected at the compressor and the low side at the POA fitting? Would it make sense to test and charge with both fittings at the compressor? Does it matter? Thanks for any guidance!
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Old 05-16-2019, 11:47 AM
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MelWff
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Looking at the 1969 factory Chassis Service Manual it shows more than one type of AC system. The Four Season and Comfortron system shows a block on the compressor with no fittings and the high side connection is near the expansion valve and the low side connection is on the POA valve. The other system is the GM Chevrolet Air Conditioning system and it shows the two fittings on the block attached to the compressor. When viewed from the back of the compressor the high side is on the right and the low side is on the left. Hope this helps.
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Old 05-16-2019, 01:44 PM
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mrl522
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Thanks for the response! My system definitely has the two fittings on the block attached to the compressor, I thought there was a second low pressure fitting by the valve but I could be mistaken. Are there any concerns vacuum testing and recharging the system right at the compressor? I thought I read somewhere that it could cause issues.
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