Air conditioning

Check the drive belt condition. If its worn then it might be slipping which is why it's only effective at higher RPM.

Chunga said:

Looking for some help diagnosing an a/c issue on a 90-91. It really only works when I get up to speed on the highway, blows cold air. But it won’t last more than 10 mins. When I got the car it worked some what. The compressor did make a rattling noise, but it did blow cold. At idle the compressor will not cycle.

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Youtube has a lot of beginner type videos to diagnose issues.

“Don’t put a crankshaft in it if it only needs an air filter”. Sounds like it has a very slow leak and it finally got low enough to stop working, as it should. Look for any leaks, first look at the valve cores on the high and low pressure fill ports. They can get slow leaks and they’re cheap and easy to replace. You might see oily looking shit there which is the leaking Freon. This is when dye in the system helps find leaks.

Cheers
nigel

1funryd, Sean, know these more than most about these cars so when he talks, listen.

Cheers
nigel

1funryd said:

Youtube has a lot of beginner type videos to diagnose issues.

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Thanks Sean

Chunga said:

Looking for some help diagnosing an a/c issue on a 90-91. It really only works when I get up to speed on the highway, blows cold air. But it won’t last more than 10 mins. When I got the car it worked some what. The compressor did make a rattling noise, but it did blow cold. At idle the compressor will not cycle.

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The problem is actually very common. In fact, it is very simple to deal with. You only need to clean the water tank and condenser. Because the water tank and condenser are dirty, the air flow is large when the car is driving at high speed, so the heat dissipation is normal, but When the speed is low, the heat cannot be dissipated in time, which will lead to poor cooling effect.