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1990 Deville A/C Bypass - help needed


lothos

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Hi Guys!

My A/C pulley is binding up. I can see metal shavings on the pulley. It's time to fix this thing before the belt breaks and ruins something else.

I have searched around for a "bypass pulley" with no luck. I can't find one at RockAuto or at the parts stores.

I've searched around a little and I've seen mention of simply removing the A/C altogether and using a shorter belt. It SOUNDS like there were three versions:

-no A/C, no P/S

-P/S, no A/C

-A/C and P/S (I have A/C and power steering)

Is that right?? Is it possible to simply remove the A/C and run a shorter belt for P/S no A/C??

RockAuto shows two different ACDELCO serpantine belt lengths for this car: 88 1/8", 86 5/8" I'm assuming one is regular and one is the California emmissions version.

Anyone have any advice?

Thanks Guys!!!

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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Searching the internet now for options.

It looks like my options are:

- bypass pulley. Autozone, Napa and Orielly aren't any help, they don't list a bypass pulley for this car. Neither does RockAuto. Autozone said they could see a Dorman brand bypass pulley but have no part number and don't carry it.

- shorter belt. I have seen reference to a 79.5" belt that might work??? Any downside to doing this?

- used compressor. Might cost around 50 bucks?

Any recomendations?

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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Do the 89 and 1990 4.5's use the same serpentine belts?

I found reference to someone replacing the standard belt with a 79" belt on an 89 4.5 to bypass the A/C pulley.

If this will work I think it's the route I will take. I have a $20 credit at auto zone and it would pay for the belt, or most of it anyways.

EDIT: AutoZone has a 79.5" belt, 795K6, for $20. I will be trying that out and will report back.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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To me it would depend on whether I could afford a compressor right now and my plans for driving the car. Since it's a 1990, that depends on the condition of the car and plans for its future. At 22 years old, it is tantalizingly close to the 25-year mark, which would make it eligible for Classic or Historic license plates, so if it is in really good condition I would figure on driving it for, say, four or five years before my next decision point.

Most cars that come standard with A/C aren't built to be driven without it and adequate ventilation in hot weather is not really possible, particularly in heavy stop-and-go traffic, so doing without A/C at all is either a short-term fix or and end-of-life functional surrender, like driving with warning lights or the MIL on. But sometimes these things are necessary and appropriate. Besides, it's late December right now. Just remember that the windshield defroster won't work well without the A/C compressor.

There are lots of options for a compressor because there is not going to be a problem in getting a matching part. The only real problem is that model years up through 1993 used FREON-12, so you will need to find someone who does FREON-12 recovery and charging to change your compressor and recharge your system. I'm not sure that sales of FREON-12 are legal anymore. Even a dealer would send out the car. If you live near a large city you can probably find two or three within easy driving distance, though.

If the short bypass belt won't clear the A/C compressor pulley, you may have to remove the A/C compressor and plug the A/C lines. This will require that you recover the FREON-12. The best option then might be to have a machine shop replace the compressor pulley bearing and put it back.

Another option that I ran into while researching your problem is a dummy A/C pulley that mounts in place of your compressor. That way you use the standard serpentine belt. This strikes me more as a permanent solution than something to get me through the next couple of months until I can line up another compressor. Apparently an outfit called Dorman makes a line of them that is sold on several web sites. Their catalog is here:

Their part #34162 is listed for the 4.1 liter and 4.5 liter Cadillac engines.

But, back to the question, how long is your bypass belt? I've found them for the 4.1 and the 4.9, but you have a 4.5, and that apparently uses a different length of serpentine belt than the earlier and later engines. If I had to buy one, I would get the one for the 4.1 and see if it fit.

If the short bypass belt won't clear your compressor pulley, you might also look at rebuilding your clutch bearing or getting a remanufactured exchange compressor. By the time you pay to have your old one removed, the FREON-12 recovered and the hoses plugged, the difference between a $15 belt or a $50 dummy pulley and just getting the A/C compressor fixed, rebuilt or exchanged can vanish.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks Jim :)

The car has been converted to 134 already and does not use the old style freon. This was done in 2001/2002 and the freon is low/empty now. The A/C hasn't worked since I bought the car, and I haven't had a car with working A/C for close to 10 years now. I don't think anyone makes a dummy pulley for this, though. I'm also assuming the A/C system has leaks and I don't want to spend the money to fix that.

The car only has 63k miles on it. It's seen better days, though. I wouldn't rate it Excellent, more like average or slighly above average. I rescued it from going to the junk yard, got the car for $750 and put some work into fixing it up and doing intake manifold gaskets and stuff (there was water leaking into the oil internally). It's not going to last forever and I knew that going into it but I love the style and wanted the car :)

I've been searching cadillacforums.com and have found 2 references to a 79 inch belt. One person measured his 1989 4.5 with a string and said it was 79 inches. I've found a 79.5" belt at AutoZone that I'm going to try, and hoping that the 89 and 90 use the same belt. I've looked at the diagram in my shop manual and looked at the car and there doesn't appear to be anything that will rub or get in the way.

Plus with my $20 credit and the belt being $20 plus tax the repair is "free" and I think I will go the cheap route for now.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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I would check the serpentine belt lengths for the 4.1 liter (through 1989) and the 4.5 (1990). If they are the same, the bypass belt should be the same too.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The only real problem is that model years up through 1993 used FREON-12, so you will need to find someone who does FREON-12 recovery and charging to change your compressor and recharge your system. I'm not sure that sales of FREON-12 are legal anymore. Even a dealer would send out the car. If you live near a large city you can probably find two or three within easy driving distance, though.

Sales of R-12 are legal. You need to have an EPA certification number to buy it and it is fairly expensive. A lot of ebay sellers don't ask for the number. Although the price of R-12 has come down in the last few years since most cars that use it are classics or jalopies these days and most jalopy owners don't care about air conditioning.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I purchased the belt last night, although I didn't get a $20 credit for some reason. Maybe I already used it, who knows LOL

The 79.5" belt is correct for the 1990 4.5 A/C bypass. The belt I got was a 795k6 (79.5" 6 rib)

The A/C pulley seems to spin OK when it's cold. There are metal shavings inside the pulley, though. It makes noise and seems to bind a little when the underhood temp increases. I got a bad rattling chain type of sound when I got stuck in traffic once. The last thing I need is a snapped belt and being stranded somewhere, the temps around here have been single digits lately.

I'll keep my eye on it, but for now it looks really good :)

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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Now that a/c is bypassed u can take off compressor. A nice warm garage would be good in mpls. Even a cold garage is not bad.

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  • 2 weeks later...

Well, well. The belt came off the pulleys today while I was almost home. Quite the surprise to not have power steering any longer :)

I'm not sure if I didn't have everything aligned right, and it worked its way off... or if the belt is slightly too long. When I got home and put the belt back on it came right off again. I got everything lined up correctly and now the belt stays on.

I DID notice that my automatic tensioner is almost all the way extended... meaning that there's room for my belt to be shorter. I noticed that there's a 780k6 belt which is 1.5 inches shorter or a 785k6 belt which is an inch shorter, and I might give one of those a try instead. Any suggestions?

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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  • 2 weeks later...

It was -9F on Monday, and the belt popped off in the cold again. I got a new belt that was an inch shorter ( a 785k6 ) and everythign appears to be working correctly now :)

The correct belt for the 4.5 A/C bypass appears to be a 785k6

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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