Ok guys. I need help. 1999 9200, 12.7. Air was shot, so I replaced everything (Condenser, Compressor, Dryer, Expansion valve, Evaporator, New Lines, Sensors). Vacuumed the system, no leaks. Hooked my 134 bottle (upside down) .Engine running with AC turned on. Both high low pressure valves on the lines open. High pressure valve on the gauge closed, low pressure valve open. Opened the freon bottle, the low pressure side went to like 75 and the high climbed to 70 neither side would climb ant further. Compressor clutch came on but wouldn't cycle. After probable less than a minute the low side high was freezing up as well as the low side of the compressor. Any idea what I am doing wrong, or where do I start looking?
1999 9200 Air Conditioning has me stumped
Discussion in 'International Forum' started by lciambotti, Nov 30, 2025 at 6:15 PM.
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Make sure the lines are all hooked correctly. If you didn’t flush the lines, maybe debris is stuck in expansion valve. No need to fill upside down. First 1 or 2 cans shouldn’t hurt it. Adding upside down can split compressor open. Not worth risking it. Be patient and let it pull the refrigerant in, can right side up. The new cans have a safety valve on them so they can’t leak out, after piercing. Make sure you’re using the adapter correctly. Might need a new style adapter. The compressor won’t cycle off till pressure is high enough. High pressure switches vary some are really high, before kicking in and cycling the compressor off. Fan switch should also kick fan on about the same time. New compressor probably has oil already in it. May need a bit more oil. Only way to know is to drain old and new compressors. 1 oz will stay in old compressor. Add 1 oz for each line. Rough estimates at best. Too much will displace refrigerant and cause compressor to run hot, it relies on refrigerant. Less oil is better than too much. I think the rule is .07% oil max. vs. refrigerant. I added 3 oz oil w/dye in mine, when I did the exact Job your doing. I had flushed the lines, replaced everything else. It holds 55 Oz. It’s a grey area, since oil usually stays in parts when replacing just a compress. Often just the high pressure hose coming out of the compressor get contaminated. Check out Video on YouTube ChrisFix AC. Make sure you’re using gauges right.
Last edited: Nov 30, 2025 at 11:33 PM
Star Rider Thanks this. -
How much freon did you actually put in it?
Rideandrepair Thanks this. -
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I don’t have a scale, but it popped up to the numbers I posted in about 10 seconds. I’ve done my other trucks and we’d add a little at a time but it took longer than 10 seconds. I had this issue last week before I put the expansion valve and evaporator on. The clutch never cycled just stayed on.Rideandrepair Thanks this.
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Check the bottle/tank which could be very low or empty. A 30lb cylinder typically weighs 20lbs when empty.
What was the reading on the low side when the freezing/frost started?Rideandrepair Thanks this.
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