Help With Ac Problem


You have a nice rear end there Dave.
15 Year Member
Nov 29, 1999
Mililani, Hawaii
I have a 2003 Mach 1, 5 speed. The air conditioning blows ice cold for about the first 10 minutes of driving. Then it stops working completely. I had a shop look at it and they said it was the coil on the compressor. I change the coil on the compressor and it is still doing the same thing. I also have changed the cycle switch. The charge in this system is correct and when this happens it is usually after driving on the freeway for about 10 to 15 minutes and then the compressor just stops engaging. The shop wanted to charge me 1500 dollars to change the compressor and evaporator because of the bad coil they claimed. I'm glad I did not do that. Does anyone have any idea what the problem might be or where I should start looking?
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you mean the clutch coil on the compressor, right? which from the sounds of it, was OK to start with. And by cycle switch, you mean what?

It sounds offhand like the evaporator is freezing up, although long distance diagnoses are tough. One possibility is moisture in the system freezing in the evaporator. That might indicate a need for a re-charge and a new receiver-dryer. On a 10 year old car, that's a good place to start, too, if it's the original. Another is that the temperature sensor on the evaporator is somehow not reading the temperature, perhaps not attached to the evaporator (this happened to me on another car; sensor fell off, compressor never stopped running until circuit breaker tripped), and letting the compressor run too long so it just gets too cold and either freezes or trips some kind of safety. How long after you stop does it need to sit before things work normally? is it more of a problem on a cool day than a hot day? Have you measured the temperature of the cold air coming out of the vents? it should be a bit above freezing. Too cold can sometimes indicate too low charge; how do you know the charge is correct? When it's working, does the compressor cycle on and off, or just run continuously, which could indicate a problem with the temperature sensor or control system as well.

You might find another shop. $1500 for compressor and evaporator is steep, especially since those parts clearly work. I see that you're an island boy too, so good mechanics are scarce, but you're on O'ahu so you've got more to choose from that we do on the Big Island. Run, don't walk, from the $1500 bandits.
I appreciate your reply. I did just have the system evaporated and recharged and it is still doing the same thing. The strange thing is last night on my way home the AC stopped working like it always does after about 10 minutes and when I got home I cooled the compressor by running the water hose on it with the engine running and then it kicked back on. so for some reason it appears that the compressor is getting hot and shutting down. But I don't know what that means because I'm not real good with AC systems. The reason I tried cooling the compressor with a water hose is because I read that on the internet but there never was a response as to why that made the compressor kick back on.
So cooling the compressor brought it back to life? anything else getting hot? was the compressor noticeably hot when you watered it down? When the system was re-charged, did they add any compressor oil? I'm wondering if the compressor is lacking lube and overheating. It does sound like you're narrowing the possibilities.
this problem has been going on for a year and a half. Only recently I took it in to get it looked at and that is when they evac'd and recharged the system. I don't think it's a charging issue at all because it did it before they did that and after exactly the same. I don't know if the compressor has a built in sensor for overheating or not as I'm really not familiar with these type of systems. it seems that a new compressor might solve the problem but I hate to spend the money on it only to find out that's not it.
NAPA lists a remanufactured compressor with clutch for $202, new house-brand for less than $250, here on the Big Island, so you should be able to beat that. I'd go with that, get somebody competent (apparently, not the guys you've been talking to) to evacuate the system, swap the part, and recharge. If the system started working when you cooled the compressor that sure sounds like a bad compressor.

I hate to say this, but I've had better treatment here from dealers than the local independents.
So tonight on my way home, it went out after about 20 minutes. When I got home, with the engine running I ran cool water over the condenser this time and same thing happened. The compressor then kicked in and started working. Something is creating heat in the system and causing it to shut down. The radiator fan seems to be working fine and the temp shows normal on the temp guage all the time.
here's a thought. buy/borrow/something an infrared thermometer (harbor freight has them on sale right now, I think) and look for very hot or very cold things in the AC system. it might give you a clue. Plus, the thermometers are dynamite for checking for a dragging brake, some cooking stuff....
A set of gauges to see what the system is actually doing would be a huge help in this case. Furthermore, if you know the pressure, you know the (approximate) temperature.
Just a WAG, but debris in the orifice valve?
A set of gauges to see what the system is actually doing would be a huge help in this case. Furthermore, if you know the pressure, you know the (approximate) temperature.
Just a WAG, but debris in the orifice valve?

Try replacing the orifice tube which controls the flow through the evaporator. Look on the web for details on location they are out there to find with a little searching. Depressurize the system first, replace the orifice tube which is like a mesh filter the size of a pencil cut in half like a golf card pencil. Put a vacuum on the system for about an hour and then recharge the system. Make sure that your compressor spins freely though, if it is not locked up then it is still good. Most of the time ac systems just need to broken down to sub systems, ie compressor, evaporator, connecting lines, accumulator also known as the receiver dryer. Also replace the receiver dryer if it old as another precaution. Also you can recharge the system your self if you can get can of 134-a recharge on the islands and also put in a small 10 oz can of compressor oil also as a preventative measure. Good luck with your ac fix.