A/C cluth, compressor or 134 conversion???

[BBrendal]

Ok heres the deal. My Blazer R12 system holds a charge and blows cold but the clutch on the compressor is tempremental. It has alot of resistance and is hard to turn by hand or will even squeal the belt. I changed and tighted the belt and its a little better but not right. If I turn the A/C on while cruising it squeals. If I turn it on at idle a chirp and its fine but go over 40 it squeals. I want to change the clutch because I dont want to break ofen the A/C system but I never done this before. Is it hard to do? Ive worked with 134 systems but just swaped the compressor on it. Not to much experience other then a charge or o ring change on r12 systems. The other option is to change the compressor but what else is involved in that? If I do that should I just convert to 134? How hard is that? Im leaning toward swaping the clutch and having a nice day. I really dont want to crack the system because there is no reason to. I still have about 14lbs of R12 so I could add if it need a shot. Any advice, direction or sugestions are appreciated.

[airdale94]

I would just replace the clutch. If you convert to 134 your A/C probably at the very least, won't blow as cold. And could, not blow nearly as cold. The problem is the condensor is smaller (front of radiator). Some vehicles have a upgraded 134 aftermarket condensor or you could try addapting one from a newer vehicle. Don't get me wrong it works, just don't expect that icy cold R12 air coming out of those vents.

If you just swap the clutch you don't need to evacuate the system. You need a clutch hub puller.

[67c10rustbuket]

I say replace the clutch and tighten the crap out of the belt. R12 cools much better especially in older vehicles. Rent the puller at autozone or other parts store and get your money back when you return it

[BBrendal]

Ok so replace the cluth it is. How hard of a job is this? Any instuctions out there?

[dracula4999]

Im not 100% sure here, but if you pull the clutch wont the freon leak out?? I know they can leak from the clutch area...im not an expert though

[rsavage]

Brian,
If the clutch is engaging when the A/C is turned on isn't it working as it should? With the belt off and engine off obviously, does the pulley on the compressor turn freely without turning the compressor? ( just grip the pulley not the front of the clutch). If so you might have a low oil problem in the system or a compressor that is going bad. You could put a vacuum on the system and draw in 4 or 5 ounces of R12 compatable oil (ester I believe) and see if that helps. The compressor will actually make some noise when low on oil, is yours? These old compressors use a lot of power to turn. Once the belt starts slipping it usually means you have to get another as I never had much luck getting them to grip good again. They need to be real tight too which is no easy feat on these compressors and brackets. Good luck,.

[FirstOwner69]

Originally Posted by BBrendal

Ok so replace the cluth it is. How hard of a job is this? Any instuctions out there?

Here's a link to a previous thread on replacing an A6 compressor clutch.

http://67-72chevytrucks.com/vboard/s...d.php?t=467590

[ChevLoRay]

Said it before, but Freeze-12 can be bought by Joe Blow and it replaces R-12.

[airdale94]

Originally Posted by rsavage

Brian,
If the clutch is engaging when the A/C is turned on isn't it working as it should? With the belt off and engine off obviously, does the pulley on the compressor turn freely without turning the compressor? ( just grip the pulley not the front of the clutch).

Yes it does sound like you just need a new belt. Now that I reread your post. And make sure to get it tight like 67C10RustBucket says.

[airdale94]

Originally Posted by ChevLoRay

Said it before, but Freeze-12 can be bought by Joe Blow and it replaces R-12.

Freeze12 is good if you don't want to update your system. But it is basically just R134A. In fact it is 75% R134A.

[ole dollor]

bbrendal : you can replace the clutch and field coil on your compressor with out loosing your r-12...if you have the tools and can do it while its on the truck, your field coil may be weak and not holding the clutch like it should....now do you know how old your compressor is, find what a clutch and field coil cost, and see what a new after market rotory compressor cost that fits your brackets , you should be able to replace your compressor for less than $200.00....my new sandon was $125.00....the old A-6 compressor took a lot of h.p to turn it, and the new rotory compressor turn easier...but cool good and you can still use r-12 or 134a.....

[BBrendal]

Update... Ok replaced the belt with a deep groove belt and tightened the hell out of it and no more squeal. Checked my pressure and it was 29low 150high. I gave it a small shot of R12 (3-4 oz)the pressure went to 31low and about 190high at 85 degrees. I put a thermometer at the vents and Im getting about 58-60 degrees out the vents. Is this right?

Plan B ... Its a Blazer! Take the top off and dont worry about A/C!

[rsavage]

The service manual indicates that your head pressure of 190 is probably good. They list it as 185-195 at 80 degrees at 2000rpms. Discharge air temp at right hand outlet should be38 -43 at 80-90 degrees. To check if you have enough refrigerant in it, you can look at the sight glass on the top of the dryer on the front of the core support. There is a little round glass window on the top of it and it may be dirty. Clean it off and watch the flow of refrigerant across it as the system is operating (engine on fast idle, controls set to max cold and blower on high). If you can see no bubbles and the sight glass is clear, there is either enough refrigerant or it is empty. Since it is cooling, it won't be empty. If you can see bubbles, it is low. An over charge can also result in poor cooling, There is a separate test for that in the manual. I can give that to you if you need it. The capacity of the system, if it was completely empty, is 3lbs 4 oz.

[ole dollor]

bbrendal: the temp needs to be at least 44 degrees to cool the truck properly....anything lower than that is a plus.....58 to 60 is not real good....but its better than nothing....your pressure sound ok on the system. take it out and drive down the road and see if it cools lower than 58 to 60 at road speeds....also check the rad. and between the rad and condenser and see if there is any trash between them. if so clean that all out real good and see if that helps....you can use compressed air and water to clean the condenser and rad. lots of it.....fan clutch is also an item to look at.....

[BBrendal]

More update... Rick I checked the sight glass. After I realized there was a cover on it I found the glass. LOL! With the system running there was what appeared to be adjitating bubbles. I added about 1.5 lbs of R12 and it brought my temp at the vents to around 48 to 50 degrees so it 10 degrees cooler then it was. The sight glass still has bubbles in it. Do I keep adding till the glas is totally clear? My pressures still look good at this point. Thanks for your help.

Ole doller... Rechecked the condesor and radiator for any crud and it was clean. On the fan clutch how is that checked? Thanks for your help.

[ole dollor]

add freon until the bubbles go away.....

[ole dollor]

on the fan clutch see if its oily in the front and see if its hard to turn after you drive it and get it hot....shut the motor off and see if it turns free or has drag on it....if it still got some drag when hot it should be ok....

[BBrendal]

Originally Posted by ole dollor

add freon until the bubbles go away.....

And that I did! I am now getting 42 to 44 degrees out of the vents.

The fan clutch turns freely when hot with a slight drag.

I need to replace the vaccum diaphram under the hood and I need the spring for the flapper in the cowl. I kow I can get the diaphram through the catalog but anyone know where to get the spring? I know this is when you switch it ti the A/C inside selection but what is the difference and which is better to use?

Thanks all for the help especially Rick and Ole Dollor! Im gonna go pull the top off now!

[ole dollor]

congrats man....might want to pull tabs off on this one ....i am so glad you got her going...sounds like you may have had several problems....cold air is what its all about.....keep cool...happy trails...

max a/c is when the door opens, when its closed fresh outside air comes in, max a/c will be the coldest, outside fresh air is good for if some is smoking inside the cab, it takes longer to choke you up.......and if it on max a/c the smell from inside the cab gets recirculated through the evap coils. and could start stinking, unless you always smell really good...lol

[rsavage]

Way to go Brian.

[leddzepp]

the under cowl (outside air) flapper should be closed with the ac on, and the kick panel (recirc) flapper should be open for maximum air volume as well as the coldest possible temperature. if all your vacuum lines are routed properly this is how the system functions with the ac on.
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