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Username Post: Ac issue        (Topic#361917)
brodybtw 
Newbie
Posts: 10

Reg: 01-10-10
07-26-20 06:27 PM - Post#2799620    

I have a 2001 suburban with the rear ac option. Compressor was shot so replaced it along with the condensor, accumulator, all the hoses, orifice tube, rear coil, and the valve in the rear since the screen was full of metal. Everytime I truly to charge it I get nowhere near enough refrigerant and the low side gets to 70psi with 110 degrees outside. I’m assuming I have some kind of blockage but if I continue to put more refrigerant in to even get to half of the spec it just cuts off constantly. Is there something I’m missing the entire system is brand new other than the evap coil in the dash.



 
59EWW 
Newbie
Posts: 13

Reg: 06-29-20
07-27-20 07:57 AM - Post#2799655    
    In response to brodybtw

Are you pulling the system down into a 29-30" vacuum with a vacuum pump to start with before you try to add refrigerant?

After the system is in a 29-30" vacuum, charge the system on the high side with liquid refrigerant to the correct amount of pounds on the data tag under the hood. You will also need to add the correct amount & type of oil back into the system, being you replaced several components, data tag should have the oil amount also. I normally pour a little oil into each component as I reassemble the system before I pull a vacuum on it so I don't have to inject the oil into the system under pressure.

The AC system is to be off during the charging and oil adding.
A weight scale will be needed to get the correct amount of refrigerant in the system while it is off. If you get the amount close, you can always top it off on the low side with vapor after you turn the AC system on.





 
brodybtw 
Newbie
Posts: 10

Reg: 01-10-10
07-27-20 09:03 AM - Post#2799665    
    In response to 59EWW

Yes I’ve done all of those things and have the scale and all of that. But for some reason even with a little refrigerant the low side pressure gets high, when fully charged it hit about 80psi. It has been a month since I did it so I can’t remember all of the numbers but the high side had looked perfectly fine.



 
59EWW 
Newbie
Posts: 13

Reg: 06-29-20
07-27-20 06:45 PM - Post#2799702    
    In response to brodybtw

What's the recommended refrigerant charge for your year of suburban?

The older models, say around 1997 with rear AC was around 4 pounds refrigerant and 11 fl. oz of oil.

If the compressor is cycling on & off, the low side pressure switch could be doing this, cause the pressure is to low, but you say the pressure is around 70 psi on the low side, not to low, so It could also be the high side pressure switch cycling the compressor on/off.

Which indicates a restriction somewhere between the compressor and the orifice tube, or the system is over charged.



 
rockfangd 
"7th Year" Gold Supporting Member
Posts: 2951
rockfangd
Age: 34
Loc: Utica ny
Reg: 04-13-10
07-27-20 07:36 PM - Post#2799708    
    In response to 59EWW

Few things here.
Need to know both low and high side pressures.
Did you put the proper oil charge in the components when replaced?
Vacuum for at least 45 minutes considering the size of the system?
It sounds to me like your high side is going too high and cutting the compressor.
Low side cutoff is IIRC only when the pressure drops too low, (close to 0).
The high side kicks off around 250 give or take which system it has.
Did you change both orifice tubes?
Installed correctly>
Sometimes if the origice tube is plugged the pipe can be too. If it was it now plugged your new orifice tube.
I hope this gives you some ideas.


Old School GM fan FOREVER


 
brodybtw 
Newbie
Posts: 10

Reg: 01-10-10
07-30-20 03:42 PM - Post#2799941    
    In response to rockfangd

Sorry it took a while to reply. Yes I did the proper amounts of oil and all of that. My system takes 3lbs of refrigerant from everything I have been told previously and found online but I can’t get near that amount. Air gets warmer and warmer. I currently have 85psi on the low side, 190 on the high side. It is 116 degrees here today.

I did replace my front orifice tube twice trying to figure this out. I don’t have a rear orifice tube I have a valve which I replaced with the rear evap coil and reattached the new bulb and all of that.



Edited by brodybtw on 07-30-20 03:43 PM. Reason for edit: No reason given.

 
rockfangd 
"7th Year" Gold Supporting Member
Posts: 2951
rockfangd
Age: 34
Loc: Utica ny
Reg: 04-13-10
07-30-20 06:18 PM - Post#2799957    
    In response to brodybtw

Ok so you replaced the orifice tube and the expansion valve.
How long did you vacuum after recovery and component replacement?
How long was the system exposed to atmosphere?
The longer the exposure the longer it needs to vacuum to boil off the residual moisture.
Exactly how much oil was put into the compressor?
And was the shipping oil removed first?
Sorry for the questions but it helps to narrow down the possibilities

Old School GM fan FOREVER


 
brodybtw 
Newbie
Posts: 10

Reg: 01-10-10
07-30-20 06:36 PM - Post#2799960    
    In response to rockfangd

System was open for about 2 hours, I had it on vacuum for over an hour. I put 6 oz of oil in the compressor since someone recommended not to put too much and the other 5 oz was added while charging. As far as shipping oil I’m not sure how much should have been in it but nothing really came out. This is my second new compressor because the first one I put all the oil in and was worried I may have damaged it so got another one to try again with no difference in pressures. No worries I understand the questions, just helps to see if I did something wrong. The orifice I replaced the 2nd time when I replaced the compressor again to see if it was dirty but it was perfectly new looking and clean. I’ve been tossing the idea of separating all of the system and maybe running a flush and pushing it through with nitrogen since I have a few bottles but not sure what is really left to be plugged up.



 
rockfangd 
"7th Year" Gold Supporting Member
Posts: 2951
rockfangd
Age: 34
Loc: Utica ny
Reg: 04-13-10
07-31-20 05:50 PM - Post#2800034    
    In response to brodybtw

I could be wrong but that sounds like too much oil for one component.
If the compressor is shipped with (shipping oil) in it it would be removed by turning the compressor sideways and with the outlet side down slowly turn the clutch and it will be pumped out.
It is extremely important to note that you never place the clutch face down (pulley side down)
The correct pag oil is then applied to the inlet side and slowly turn the clutch to allow the proper amount to be put in.
I specialize in AC. I probably work on upwards of 60 per year.
Every once in awhile I get stumped up but usually a walk away and come back to it figures it out.
I am going to look into the complete capacity and get back to you.
This may be a dumb question but could the orifice tube be installed backward?
And the bulb on the expansion valve is in the correct position?
If vacuumed properly a few things are on my mind.
too much oil
bad compressor (doubt it)
Restriction on outlet side of compressor.
The list is smaller because your high side pressure is not pegged. Usually a restriction pegs high side pressure unless it is near the compressor
I see 11 oz of pag 46 so far. So 6 oz may be right. Still looking further

Old School GM fan FOREVER


Edited by rockfangd on 07-31-20 07:11 PM. Reason for edit: No reason given.

 
brodybtw 
Newbie
Posts: 10

Reg: 01-10-10
07-31-20 09:18 PM - Post#2800051    
    In response to rockfangd

No the orifice tube only fit in one way, plus I double checked online being paranoid. The bulb went right back on where the old one was. I’ve always done friends and family’s vehicles and never had an issue until now, I even did my dads 07 silverado after with no issues luckily. I’m stumped myself, if I made a mistake somewhere I’d sure be happy to find out what it was. I could always recover the refrigerant and pull a vacuum on it again and go from there. I do commercial ac so luckily I have all that equipment. Maybe I’ll pump it down anyway and start checking between everything. I’ve literally replaced every part but the dash evap coil but I guess it’s possible that I have an issue with a new part, wouldn’t be the first time on this truck.



Edited by brodybtw on 07-31-20 09:20 PM. Reason for edit: No reason given.

 
rockfangd 
"7th Year" Gold Supporting Member
Posts: 2951
rockfangd
Age: 34
Loc: Utica ny
Reg: 04-13-10
08-01-20 05:02 PM - Post#2800100    
    In response to brodybtw

Ok lets take a step back.
when the compressor cuts on and off I would really like to know what the pressures are.
I wish I could see it in person because it can be difficult in translation.
It should not cut off unless the low side gets too low or the high gets too high...
If it is cutting off anywhere but that I would like to know. It may be a faulty pressure switch.
Would also explain why it will not take enough.
Compressor is not staying on long enough to pull proper charge.
Please post specifically.
High side pressure when compressor cuts off
Low side pressure when compressor cuts off.
How long between cycles (on, off, on)

Old School GM fan FOREVER


Edited by rockfangd on 08-01-20 05:03 PM. Reason for edit: No reason given.

 
brodybtw 
Newbie
Posts: 10

Reg: 01-10-10
08-01-20 05:27 PM - Post#2800102    
    In response to rockfangd

I’ll get you those numbers as soon as I can, I may have worded wrong somewhere but it will take the full charge but the air coming out of the vents sits at like 70 back when it was 90 out and I did all that work. The compressor kicks off if you hit the gas a little and the high side comes up but I cannot remember those pressures at the moment. Compressor definitely felt like it was working too hard though, lugs my 5.3 down way more than my friends 4.8 silverado does.



 
rockfangd 
"7th Year" Gold Supporting Member
Posts: 2951
rockfangd
Age: 34
Loc: Utica ny
Reg: 04-13-10
08-01-20 05:58 PM - Post#2800105    
    In response to brodybtw

When revving the low side should decrease and the high side should increase.
That last sentence makes me question the pag oil in the compressor.

Old School GM fan FOREVER


 
bobb 
Super Senior Member
Posts: 5660

Loc: paradise
Reg: 09-05-03
08-02-20 10:20 AM - Post#2800141    
    In response to brodybtw

i would check line temps to see if they are consistent. im reading through all this and keep thinking restriction in the suction line feeding the compressor.

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
brodybtw 
Newbie
Posts: 10

Reg: 01-10-10
08-02-20 06:19 PM - Post#2800173    
    In response to rockfangd

Keep in mind that 2 compressors in and I still have the exact same problem. This has also been a couple of months since I did this and it still acts the same. The last new compressor I took out to put the one I have now in just to see if that was the issue went into a friends truck and is working great the same way I installed it into mine. Didn’t change my outcome at all. I’ll have my guages back tomorrow and can check temps while I’m at it also



 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25194
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
08-04-20 08:53 AM - Post#2800284    
    In response to brodybtw

Was the fan clutch replaced? How old is it? I replace fan clutches with A/C system rebuilds. I'm surprised how many people drive around with bad fan clutches. Owners also comment that engines get hot at idle when driving. I tell them the clutch is toast. Plus it will help with cooling and A/C temps by replacing it.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
rockfangd 
"7th Year" Gold Supporting Member
Posts: 2951
rockfangd
Age: 34
Loc: Utica ny
Reg: 04-13-10
08-04-20 06:15 PM - Post#2800331    
    In response to gchemist

If the high side pressure was higher I would think of that but want to get current numbers.

Old School GM fan FOREVER


 
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