Auto Repair Help
Carl’s Corner – Auto Repair Help


By Carl O’Reilly

The air conditioning system is not cooling as expected. The air conditioning system may require an extended period of operation to reach the desired output.

Low refrigerant level is the most likely cause of poor cooling from the air conditioning. If there is no cool air coming from the air conditioning system, an electrical malfunction could be the cause. A defective relay, compressor clutch coil or damaged compressor are all possibilities.

The air conditioning system is equipped with safety switches that automatically turn the compressor off when the A/C refrigerant level becomes low. This prevents compressor damage, since the lubricant for the compressor is circulated through the system by the refrigerant. When the pressure switches are activated, power to the compressor is interrupted regardless of the position of the A/C dash switch. Recent regulations have prevented most consumers from doing the repairs. Special equipment is now used to remove the refrigerant, referred to as “evacuate” prior to opening the refrigerant system. Special leak detectors are used to detect leaks around hoses, fittings, and valves. Once pinpointed, the leak will have to be repaired once the existing refrigerant, if any, is removed.

The refrigerant system is under high pressure at all times. During operation, the high pressure side of the refrigerant system can reach pressures of over 275 PSI. Use extreme caution when working around the A/C system. Never disconnect or vent the refrigerant to the atmosphere. Refrigerant can cause extreme frost bite or blindness if it comes in contact with your skin or eyes. Repairs to the A/C system are best left to trained service personnel using the proper test and service equipment. Repairs can be made by the consumer, however, the system should be evacuated using the proper equipment by trained service personnel prior to any component replacement. After the system is repaired, it will have to be recharged using the same type of equipment.

18 Responses to “Diagnose Ac System Doesnt Blow Cold Air”

  1. Brian says:

    I recently tried recharging my a/c system (5.3L chevy Silverado truck) with an “easy charge” system from my local auto parts store (attaches to the low side and press the trigger). I think I overcharged it because now the compressor clicks on for a couple seconds then off and only warm air is blowing. I bought a set of guages and an evac pump and evacuated the system, put in a new expansion valve, and tried it again, same result. The reading on the guages are LOW SIDE=high & HIGH SIDE=low. Did I f-up & need to replace the compressor/accumulator?

  2. Mr Sames says:

    Due to the expansion in the air compressor there are very advanced compressor are available in the market with the low risk factor and high power facility.

  3. peter says:

    I evacuated the system and disconnected the lines to check that the condenser isn’t plugged by blowing by filtered air through the system.

    The low and high side switch works. If it has too high of a charge, the compressor won’t turn on. If it has too low of a charge, the compressor won’t turn on.

    I replaced the drive belt and adjusted the tension during installation.

    The central console switch(s)work.

    I’m not sure if the receiver / dryer on the R/F fender well is bad or the evaporator under the dash is bad.

  4. Brandon says:

    I have a 2005 Chevy Avalanche. It is a 1500. My AC has always been a little weird. At times it would blow hot air, but would stop after the car was turned off and on. However, now it only blows ambient air. It was over charged a bit at one point, but no longer. I checked the electrical box for the AC fuses. I found out that the AC Compressor 10 A fuse will immediately pop when I turn on the AC, but air still blows out the vents.

  5. jim says:

    I have a 2008 town and country. My ac is blowing warm air. There are no leaks that I can see, I also used the dye and UV light. The compressor engages when ac is turned on. What can be the problem ?

  6. Brittney says:

    Ive replaced the conpressor and condensor and still blows very very hot. Any ideas as of why.


  8. henry says:

    hi i have a 1991 chevy s10 i had a certified ac technicion install all new parts in my truck i even changed the radiator thermostat water pump fan clutch i even installed two electric fans nfront of the condensor and it keeps blowing my compressers within hrs and will not blow cold air thru my vents i dont know wat else to do evben the tech cant figure out wats going oni need help

  9. george savoy says:

    Hi , My name is George I have 2003 S10 pick up Air Condition is working , I just change new Blend Door Actuator part and still blower hot air but I check Air Compressor and Condenser is working well and cold but inside truck Dash board blower hot air while AC is on ! I Cant find what is Troubleshooting ! So can u feedback me Help Please !Thanks George

  10. Joe says:

    I have a 5.3 1999 GMC 1500 Pick up
    The AC blow cold for about10 minutes then blow hot. shut truck off for a while then blow cold for 10 minutes then hot. Had it recharge no change. Was told it might be the clutch kicking out when it gets hot.

  11. albert says:

    the air blows but it doesn’t throw cold air and I can’t hear the a/c turn on, on the engine e

  12. Ganiyat Ismail-Balogun says:

    My car a/c will work for a minute then stop for 5minutes then pick up again .my car is sienna 2001 .pls what can I do

  13. Robert Willbee says:

    I have a 2001 chevrolet silverado,only blowes ambient air
    on the recycle side but vary cold air on the maximun a/c side when the a/c is on the recirculating side the accumlater has no build up of moister on it, could this be low pressure, cause it is not cooling
    any help would be greatly appreciated

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