A/C squealer

[Robert Bartsch]

a c squealer robert bartsch i m restoring a big block coupe with factory air conditioning when i purchased the car the a c system was not complete therefore i purchased the following components a rebuilt compressor poa valve expansion valve receiver drier muffler and hose assembly high compression hoses fan belt after i installed the new components i took the car to an a c shop that evacuated the system and then filled it with r freon as a result of the charge the compressor locked up producing a very loud squealing noise when the compressor clutch was engaged the fan belt pulley is aligned and is tight the service shop indicated that the likely cause is the compressor they pumped the system down and i replaced the rebuilt compressor with a new rebuild the proper amount of a c compressor oil was used when the compressor was installed i then took the car to a jiffy lube center they evacuated the system and charged the system with r the compressor locks up the same as before gauge readings on the low side are lbs no reading was taken on the high side no gauge was available ambient temperature was approximately degrees technicians at old air products fort worth texas indicated that the likely cause is a bad radiator fan clutch however the squealing occurs when the car is dead cold and the fan clutch appears to be working properly no engine overheating other suggested problems offered included i antifreeze is being circulated through the heater core causing the a c evaporator to block freon flow ii a stuck poa valve or iii a stuck expansion valve normal low side pressure readings are about lbs at the carlisle pa car show i noticed that other big blocks a c cars did not have a manually operated heater hose valve that is located between the engine intake manifold and the heater core i believe this is in the open position on my car i cannot turn the valve lever however in addition the service manual indicates that the gm four seasons climate control system shuts off the water flow from the engine when the a c system is operated i assume this is a vacuum operated feature since the compressor lock up occurs when cold i suspect it is not a heater core related problem

[Jack H.]

Re: A/C squealer

re a c squealer jack humphrey long post with lots of considerations bob first i have a ' sb a c car and if you want to take this conversation off line feel free to go one on one with me because there's a lot to cover but for starters what the heck is r we all know r trademarked freon by dupont is the factory refrigerant to use squealing sure sound like belt slipping many of these older cars got worked over pretty good and odds you've got correct set of original pulleys in all positions including the one on your new re built compressor unless it was a delco rebuild is slim the only way to verify is to pull all the belt pulley and look for the gm p n wacked into each pulley on the backside and compare to the assembly manual aim the in line heater shut off valve is a vacuum operated assy and you can get replacements at napa it will not cause belt squealing it will only cause heater not to get hot water from the engine block if its shut with the cost of r refrigerant you can't afford to do hit miss diagnostics need to verify the whole system before you pump 'er down i'm lucky because i joined an ncrs chapter and one of our members is an hvac fellow i got my ' running within only five attempts working like you and found umpteen things that had been dinked with by prior owners and repair folks over the years