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Re: Rebuilt truck a/c not cooling as it should. by Mallie
Post New Message Hello Robert, there is not enough info to properly diagnose with any degree of accuracy, but on site it not a problem for anyone with basic AC knowledge. If your AC folk can't tell you what the problem is, get another shop. There is a limit to what any AC can do, but it does not sound like your system is not performing within the designed limits.
As mentioned, you are going to have a specific temperature drop from the inlet evaporator air to the temperature of the air coming out of the ducts, based on conditions. Just duct temp is really not very useful alone.
Ask you AC expert what the super heat is, and the suction pressure, head pressure, cabin temperature and ambient temperature of entering condenser air.
Assuming the condenser is getting sufficient circulation, you can narrow it down real quick. A check of high pressure saturate temperature, and the sub cooing will tell that too.

If you have low suction, and high head, high super heat, it is a restriction, probably metering device or filter. If you have the same pressure combination, and low super heat, it is air restriction. If it is low head and low suction, and high super heat, low charge. You did mention freezing, and this can not happen if the suction pressure is above freezing on the Pressure/temperature scale.

First guess, Freezing, low suction, By the system being open, I would suspect the possibly of a restriction. If it is a cap tube, usually pretty easy to get to and check. The low suction pressure should have a low cut out, anyway. I think it is supposed to be changed on some conversions. Low charge can also cause this.

Second guess, The water is circulating in the heater radiator. Clamp it off by folding it and applying a spring clamp.

Third Guess, There should be a means to allow outside air into the system normally, but should provide a way to only return inside air, usually marked as max, or recalculate on the controls. If you are cooling the at high temperatures, you want to recalculate the inside air, instead of outside. Big difference.
Mallie
All Messages in ThreadAuthorDate
Post New MessageRebuilt truck a/c not cooling as it should. Robert 7-31-02  
  Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Joe 7-31-02  
  Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Sam Watson 8-1-02  
  Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Joe 8-1-02  
  Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Mallie 11-22-02  
    Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Robert 7-31-02  
      Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Joe 7-31-02  
        Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Parker 8-3-02  
          Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Sam Watson 8-4-02  
            Reply to MessageRe: Rebuilt truck a/c not cooling as it should. Rob 9-9-02  
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