A/C help ,,, less than optimum performance

rfehler · August 18, 2014

I'd venture to say you are undercharged

I agree.

Is it best to measure cab air/evaporator temps with the cab open or closed? I've always done it while closed to get lowest temp readings and to see if the system cycles prior to freezing. (36*)

And, how exactly do you test your fan clutch? When at operating temp, I've always just felt the clutch resistance and made sure the fan wouldn't free spin more than about 1/4th of a turn.

Thanks again.

Robert

rfehler · August 18, 2014

Ok men, here's what I have ...

Ambiant 91*

Humidity 57%

Cold static pressure 93

Cold idle - low 40psi High 160 Air 52*

Warm idle - 35/180 Air 50*

Warm 1500rpms - 28/215 Air 38*

Warm idle again - 34/220 Air 47*

Referigerant added at idle - app 3-4oz ... No change.

1500 rpms not much different 28/235 Air 38*

Added more ref. - low side at idle no change. High 255

1500 rpms - 28/265

Stop.

System quit taking ref. with approximately 10oz added.

Warm static pressure 65psi.

Basically nothing changed after adding approximately 10 more ounces of refrigerant. (12oz can getting close to empty) It wouldn't take any more.

???

Although I flushed the evap twice and concider I did so very thoroughly, is it possible that it is clogged? Other than the lines thats the only thing I didnt replace. What would it being clogged to to my pressures? I though if anything in the system was clogged you would get higher pressure. Not low like I'm getting.

That being said, we all know the evap is on the low side after the guage port. If the evap was clogged wouldn't the back pressure cause the low side to be high? I did get pretty good air flow through it while frushing.

It's got to be something else.

Maybe as previously suggested it "is" the compressor. Speaking of which, What is the difference between a Delphi and a Denso? When I got this truck 3 years ago it did not have a compressor on it. I bought a Denso and it worked fine till it developed a leak. This time I bought a Delphi. Just wondering if the different compressors could be my problem? The only differance I'm aware of is the styles of clutchs each one uses and that one has a fixed clutch wire connector and the other has a short pigtail connector. Nether of which should cause the problems I'm having.

When buying an aftermarket compressor the question if you have a Delphi "style" or Denso "style aways comes up. My question is why that's important? Take O'Riellys for example. Their store brand is Murray. Under each Murray comp the discriptions says "with Delphi comp" or it'll say with Denso Comp. Both will bolt up but there must be some kind of difference other than the style clutch and wire connector.

Any other suggestion?

Robert

txab · August 18, 2014

If you want to know how to test your fan clutch, look at this post. It has everything I'd type in. The fourth test is the one that will tell you for sure. The rolled up newspaper test works. Just have to be very careful, perform at your own risk

http://forums.pelicanparts.com/bmw-6-7-8-series-technical-forum/512843-how-test-visco-fan-clutch.html#post5028839

If your clutch has more than 75k, it's probably time to change

rfehler · August 18, 2014

Regardless of the fan clutch there is still something wrong with my ac system. I know the fan clutch is an important part of the system but it should actually only come into play with the engine at normal operating temp sitting still at idle. As far as the condencer goes, going down the road it gets plenty of air. My problem is across the board. Hot, cold, on the road or even with a squirrel cage fan on high blowing through the condenser. It doesnt seem to matter.

I'm leaning toward taking this compressor back and starting over. New compressor, dryer, o-tube and reflush everything. Cha-Ching!!! More $$$. Perfect!

(Only reason I'm replacing the dryer again is because I know I put 4 oz of oil in it. If thats OK I'll continue to use it. If not its coming out. (See question below)

With a new compressor, dryer and o-tube, where exacly do you put the oil into the system? i know the sysyem is supposed to have 8oz of oil. The new compressor requires 4oz. Where do you put the other 4oz? I've read the other 4oz should be put into the dryer. (in which I did) Read somewhere else 4oz goes in the compressor, 2oz in the dryer and 2oz into the condenser. (did that the first time I charged it and got really high pressures) Decided putting oil in the condenser may have clogged it resulting in the high psi I got. Apparently everybody has their own way of doing things. I want to know the right way.

This time I'll be using an ac RRR machine to evac and charge the system. No more guessing with disposable cans. And yes, other than initially putting the 4 oz of oil into the compressor, the machine will add the additional 4oz. But for future reference I still want to know the correct "shade tree" way to put oil into an ac system.

txab · August 19, 2014

Mist water across condenser and see what happens. Delphi makes a good compressor, btw

When you're flushing, what is your procedure? What is your flushing agent?

rfehler · August 19, 2014

OK, I'll try misting the condenser. Shouldn't that raise my low side and lower my high side?

I realize charging by guessing how much refrigerant I put in and going off of guage readings is a crap shoot at best. But its all I had available at the time. Things have changed since then. One of my sons just started a new job at a auto repair shop. And yes, they have an ac RRR machine. I'm going to take the truck up there in the next couple of days to evac and recharge. Even if my capacities are a little off at least I'll have the correct refrigerant weight as a base line to start with.

Thanks for the thumbs up on Delphi Compressors. I don't really think it's the problem. I just figured I could eliminate it as a possibility by swapping it out.

I used AC PRO Flush and Clean from O'Riellys. It comes in a quart jug. I pour a little in, let it sit for a couple of minutes and blow it out with air hose. Repeat numerous times. I'm flushing it both with and against the systems flow. Starting with against the first several times.

I still need to know about putting oil and how much into the dryer. I'm afraid what I read about putting 4 oz in it was wrong and its over filled creating restricted or sluggish refrigerant flow. Or, would that 4oz of oil have circulated thru the system by now?

rfehler · August 20, 2014

Bought a new fan clutch today. No more guessing if parts are good or not. I'm done with guessing on this thing.

BTW ... Pretty sure y'all were right. The new clutch definitely feels tighter than mine. I'll install it tomorrow.

I'm still considering taking this compressor back for an exchange. Too many things haven't been right to take a chance with it.That and after the high pressures I was getting the first time I charged the system and then evacuating it to reflush everything, I found little pcs of metal/brass on the new orfice tube. Maybe the metal was still in my sysyem from the old compressor or maybe it came from the new one. ??? Again I'm done guessing. It also makes a little more noise than I like. So even with the possibillity this one failed, (not really thinking it has) I'll go ahead and get another Delphi and see how it does.

Looking again at the two different condensers the new does look like it could have a "little" more capacity. The question is how much more? I'm going to start out by charging the system with the recomended 30oz of ref and see where my pressures and air temps are. Only then if needed I'll add an additional 2oz at a time. My hopes are not to exceed 32oz.

If I'm wrong about the additional capacity then I'll only be 2oz over charged. If I'm right I could be right on or possibly an ounce or 2 under. Damn. There I go guessing again. I'm hoping an ounce or two either way won't hurt me too much.

Needless to say everything will be getting flushed or replaced again. For pease of mind and as little as they cost I'll likely buy another new orfice tube and accumulator. As with the original purchase new ones may be required for the warrenty on replacement compressor.

I know this sounds like I'm rambling. But my hopes are when you guys read this you'll pick up on things I may be doing wrong and advise me before I end up right back where I am.

Thanks again guys. I've leaned some valuable information from you. Although I'd still appreciate your replies to a few of my previous questions, I'm pretty sure I've got this thing on a down hill run. I'll let you know how it turns out.

Robert

dewfpo · August 20, 2014

I've been in Jury Duty the last few days and have not been on my computer.

I don't have the exact specs in front of me but the compressor should have a tag on it saying how much and which type of oil to add or…. if it already has oil in it. The rest of the system oil should be added to the dryer.

I'm not a big fan of Hayden Severe Duty fans. They do their job but are was always engaged. They 'roar' all the time.

When checking vent temps on Max A/C doors and windows should be closed.

I'm not sure what other questions you have open that I may be able to answer.

DEWFPO

rfehler · August 21, 2014

Sorry to hear you had to pull Jury Duty. I wouldn't wish it on anybody. Last time I went we were imprisoned for almost a week. I'd do just about anything to keep from having to do it again.

Your right. The fan does make more noise than before. But I'm ok with it for now or at least till I get this ac prob worked out. Might swap it out sometime down the road. Meanwhile I definitely know it's working.

Thanks for answering my oil question. That means I did at least one thing right. Now if I could figure out what I've done wrong we'd be in business.

I've had a change of heart on unpluging this compressor from life support. Lol. Considering it has a 2 year warranty I might as well give it a second chance at life.

I'm going to evac the system, inspect the orfice tube and decide from there my next move. If its clean I'll pull a vacuum and recharge the system with the correct amount of ref and run it. If its not clean ... you know what I'll have to do.

Seriously, what else can I do? I've done everything we've discussed other than having exactly the right amount of refrigerant in it. The ac machine I'm going to use should take care of that problem.

Then if its not working like it should ... I'll start over by flushing the system again and replace the compressor, dryer and o-tube.

Speaking of Orfice tubes ... Apparently GM used not less than 3 different o-tubes in full size vehicles. The first being the little skinny one we've used for years. The second being just a fatter version of that one. And the third being a fat cigar looking thing called a GM Porous Plastic PPOT Orifice Tube.

When I bought the tube for my truck they sold me one of the original skinny styles. Then when I pulled mine out I saw it was the plastic porous style tube. When I returned the first one they had to look at a newer model truck (2003) to find one that fit my truck. I say the right one. They sold me the fatter style tube. Not the porous style like was removed. From what I've read the only differance in the two tubes is the porous one was designed to reduce the noise the refrigerant makes when passing through it.

What I'm getting at is that I'm a little curious to know why my 2000 truck has a newer style tube in it? All I can figure is the previous owner replaced the hoses with newer model ones. Why? And more importantly, if the ac system in my truck originally had hoses with the skinny style o-tube, would the newer style hoses and o-tube make a differance in my ac performance?

Thanks again.

Robert