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Weird A/C problem with 280 turbo


roger.svoboda

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Got a 81 turbo zx that I put a 5 speed into. Runs great EXCEPT after about 8-10 miles running with the A/C on the engine starts surging. Either losing spark or fuel too lean/rich? When it starts surging you can put the thermostat to high which should disconnect the compressor and electrical but has no effect on the surging problem. As soon as you move from A/C to another climate positiion the surging ceases and car once again performs well. Checked all the vacuum lines I could find and seems okay. Car only has 138k on it and runs strong (when A/C not on). Got boost up to about 5psi. Happens in any one of the A/c selections. This is a manual (not the fancy one) climate control. Any one got an idea??

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No As I pointed out when I turn the temp control all the way high this de-energizes the clutch which drives the compressor thus it is just freewheeling - even if the compressor were completely frozen if the clutch is not energized nothing happens as far as what the engine senses. I also find it hard to believe that a 5 HP compressor which is belt driven could affect a 180 HP motor to the extent of what I am seeing. At some point the belt would just wear through.

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I may be wrong - have been before and will be in the future - but surging to me implies a big vacuum leak somewhere.

 

I would think it would be between the vacuum tank on the passenger fenderwell and the actual AC system.

 

As a test, block off the (should be single) vacuum line where it comes into the passenger compartment (behind the radio console I believe).

 

I converted my Auto Air system to manual and only use one line, so I think you should only have one coming in.

 

Also, make sure that the hoses in the engine compartment aren't crumbling.

 

I have just recently replaced all of mine due to this very issue. The ends of the lines on the vacuum tank kept breaking apart until they were too short to reach.

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