Engine Stopping when when turned to defrost

[zrusscher]

I have a 1991 4 door Eddie Bauer with manual transmission and manual 4x4 diff and hubs. The engine runs fairly well, although slightly rough, until I turn the climate control to defrost, the engine immediately cuts off with some whining from the belt. This happens even when the A/C is off and the fan is off. It doesn't happen on any other setting except a combination of mostly defrost and some direction to the floor. The engine will re-start with a turn of the key when on defrost, but then will shut off within 2 to 5 seconds. Recent work done includes replacement of the A/C compressor, the belt, belt idler, belt tensioner/pulley, the battery, and the alternator. Any help would be appreciated. By the way, the more detail, the better, as I am not experienced at 16 years old.

 

[bwryan]

The cutoff with belt whine would make me think the A/C compressor is seized, or the engine is running so poorly that it can't handle the additional load of the A/C. On some vehicles, I think including ours, when the climate control is set to defrost it automatically turns on the A/C, even if it is otherwise turned off. It sounds like you're saying the engine cutoff doesn't happen when the A/C is turned on while set to something other than defrost? When you do that, is the temperature set all the way to the coldest position, to make sure it really turns the A/C on? Is the replacement compressor a new (rebuilt) unit, or a used one? The quality of new parts these days isn't great, sad to say. But in any case, having somebody watching the A/C compressor when you set it to defrost would be my first step.

 

[fosterzcj]

If your compressor is seizing then you can turn off the defrost setting while idle and unplug the compressor whike running. I had a ranger that was doing the compressor knock when the ac was running and that's what I did. You can then turn the defroster mode on and use the heater and then crack the drivers window to vent out the hot moist air. I've done this for years (5 on a ranger and 10 on a civic) and it'll work keeping the windshield clear without hurting anything.

 

[zrusscher]

UPDATE: The truck also shuts down immediately when the A/C is turned on. To my knowledge, the A/C compressor was rebuilt, and the old one was also seizing before (at all times), which is why it was replaced. Not that I really know what to look for, but I saw the compressor when the engine stopped, and the compressor did stop and drag the belt. Thanks for the input.

 

[zrusscher]

PS: After the A/C compressor was replaced, the A/C system was in good order. Also, it was running fine until my DIY battery and alternator swap, though maybe I haven't used the defrost/ A/C for a while.

 

[fosterzcj]

The problem with compressors is when they haven't been used in a while they can seize even if they were good before an extended period of non use.

 

[zrusscher]

Is there a way to repair the existing one. The maximum the A/C wasn't used was maybe 3 months. Thanks. By the way, the Explorer is in southern California, so no extreme temperatures.

 

[FordFlintrock]

When the original compressor failed it likely contaminated the system with burnt dark oil and metal shavings. For replacement compressor the manufacturer requires a system flush of lines and components in addition to replacement of accumulator, orifice tube and often the condenser per warranty.

 

[mountaineer2004]

Sounds like an expensive job to get the a/c properly running. If it were me, I'd install an a/c bypass pulley and move forward. Maybe you're rich, but at age 16 I would be ecstatic just to have transportation. People have few needs, but many desires. This is not a need. YMMV

 

[zrusscher]

Thanks, I'll try the bypass pulley.

 

[mountaineer2004]

You're welcome. You may not even need to buy and install the bypass pulley. My ac compressor recently stopped working (cooling) but its pulley was okay, meaning no trouble at all when ac was off, so all I did was pull the ac fuse.

If your car is okay with ac off, simply pull the relevant fuse to solve your problem. If the original compressor pulley is causing trouble, you'd need to install the bypass pulley.

If you do need to get the bypass pulley, it's the Dorman #34184 part you need for your '91. Good luck.