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That is correct, my 1990 has the same setup.

No! on 1989 model year - low and high pressure switches mount on compressor, fan pressure switch near the dryer

Normal system voltage output should be approx 14.2v, one can check that with a simple voltmeter. that voltage level is seen on the voltage gauge in the cluster, if one loads up the system at engine idle note with the meter what the system is dropping off to. I've been where you are, to get around this 2 years ago I replaced the original output 105 amp alternator with a 140 amp unit. Idle voltage issue was significantly reduced.

The v5 has only one single high pressure blow off valve mounted into the back end of the housing. The system low pressure switch is as you noted next to the receiver/dryer.

about 12v and below

low and high pressure switches mount on compressor, fan pressure switch near the dryer

How much is it dropping? These cars had a rather undersized charging system from factory. Especially a TGP with the terrible braking system.

The pressure switch is a necessary device to prevent the compressor engaging when there is not enough refrigerant in the system.

Yep, that's what happens at idle, the idle speed needs to be at least 800rpm to combat the load on the charging system. In those situations put the trans in neutral, raise the engine rpm to get the charge rate back up. Something one can do is to pull out the secondary fan relay to prevent the secondary fan engaging. The secondary fan only engages when the a/c is on, it very seldom engages for engine temp cooling purposes as it doesn't engage until the engine temp is near 220F degrees. The side effect of this is the condenser will not dissipate as much hot air as both fans running.

Was this the mode from the factory? then what is the purpose of the pressure switch near the dryer?

But it turns out that if the car is stuck in a traffic jam at idle speed and the brakes are pressed, and plus two fan, the voltage drops alternator - new 105a

Super stoked for this one! Just picked up this 93 tonight. One owner Michigan car! Not a spec of rust accept for around the windshield trim! Undercarriage looks virtually new! Has been sitting since 19, so some gremlins to work through! New top, but not a documented time of replacement. Has the usual oil leaks etc, and a horn / headlamp issue. But I am looking forward to getting acquainted with it! I think it’ll be a good pairing for my 95 as well.

what if i js took out the rear monoleaf and put some spacers would it work ? i mean the ride will obviously be bad but as long as it will actually drive like that i think i’d be fine with that

Not really any of those as I recall. once upon a time someone made lowering leafs, pretty sure unless you find one of those your only option is DIY coil overs, Its been done here but honestly I was never into that so I can't speak to it

When I first started charging the A/C system, the driver side fan kicked on. It might have kicked on when I actually pressed the climate control panel. As I started filling the system...I think with the start of the 2nd bottle of freon, the compressor kicked on as well as the passenger side fan. Yes, when I'm on the HWY or Interstate, I'm assuming both fans have shut down long ago by that point. I can then hear them, (and feel a little bit), when I'm back in city driving mode.

I should also add that the coolant fans engagement is speed dependent, when the a/c is on the pcm will disengage the fans as the vehicle speed increases to the point when they no longer need to be.

anybody know the cheapest quickest way to completely drop the rear of a cutlass with the mono leaf suspension? ps no judging i recently picked a up a running/driving 92” cutlass supreme for 500 dolla so im trying to make something to scrape the floor

I just rebuilt the A/C system in the International and yes, both fans run when the A/C is on. The fans and the compressor is doing exactly how 55trucker is describing.

Indeed it is........ both the primary & secondary fans will engage. The low pressure sensor engages the entire system when the system is above approx 40lbs, the compressor does NOT cycle, once engaged it runs 100% of the time the a/c is turned on (depending on the volume of system charge).

TGP 1989 When operating without the air conditioner on, everything is fine. But when we turn on the air conditioner, even on a cold engine, both the main and additional fans turn on immediately. The question is - is this a normal operating mode? After all, the pressure sensor should be responsible for turning on the fans, but the control unit ignores any state of the sensor.

This thread seems old. Did anyone ever find replacement top header seals. Looking for a 1992 cutless supreme

Yep, I've also read it's not reversible, which is pretty annoying to have to clean it with alcohol all the time. It's been out of the sun for the last 5-years, but the damage is already done. Also gets pretty hot in the garage and I'm sure that doesn't help. Only permanent-ish solution I could really think of is to have it wrapped in color-matched leather. Might look nice if professionally done. Only thing is if leather needs to be glued down, it wouldn't stick for long if the vinyl underneath keeps sweating. Maybe it would need to have the vinyl stripped off, then built up and sculpted with some other material to the right shape so that part can be leather-wrapped. Sounds like very high cost. Other parts of the car would need attention before I go to that extent to fix it though.

This is something that I remember hearing about years ago about when modern day cars would age. The plastics would decay and the first stage is when they get sticky. Then over time that stops and the plastics dry out and get hard and start to crack. I don't think it's possible to reverse this process once it get started. I know it's a big issue on foreign cars that are around 20 years old. They always seem to get the sticky buttons. It is just going to keep happening. The best thing would be to clean, protect and keep it out of the sun to reduce the decay rate. Unfortunately these cars don't have a lot of aftermarket support, so getting new interior pieces isn't really an option. Buying a used one is likely going to have the same issue. Pretty impressive the car went 30 years without having that problem. Lasted much longer than most.

It's a bit of a bummer, my 89 Cutlass door armrests are very gooey and sticky due to sweating plasticizer. It's been going on the past few years. I've read this is how vinyl decomposes, and it won't stop until the vinyl becomes hard, brittle, and cracks. I've been cleaning it off with isopropyl alcohol in the meantime, but it's just temporary. Going to try cleaning it again, then putting 303 Aerospace Protectant on it. Anyone else have this problem and found a solution that works?

This is all I could really find for free. https://charm.li/Oldsmobile/1992/Cutlass Supreme FWD V6-189 3.1L/Repair and Diagnosis/Heating and Air Conditioning/Evaporator Core/Service and Repair/ Although I 100% agree that you should get the genuine GM service manual. Well worth the $7.50+shipping. https://www.ebay.com/itm/235434976664