A/C question

Poon · Jul 1, 2011

Last year my A/C had a leak in compressor, so I replaced comp, dryer, and oriface tube, charged it up and it was cool but never really got cold. After that I took it to 3 different shops and they all said "that just as cold as this big old truck will get with the temps in the 90's here". Since then I have replaced oriface tube with the severe service one, did the ball valve heater core bypass, and took the evaporator core out and cleaned it ( it did need cleaning). Blender door and fresh air door are working properly. After the recharge it was a little better but no big improvement, temps coming out at around the 60 deg range. I got tired of their answers to my luke warm air so I broke down and bought some gauges yesterday and here's what I have come up with.

At idle my pressures were 38 low side and 200 on the high side.
at 2000 RPM the low side would drop to 29 and the high side would also drop down to just over 150.

The only knowledge I have of A/C work is from reading on forums. I'm thinking this means bad compressor. Let me know if anyone thinks I'm wrong before I spend the money on another new one. Thanks

Tom S · Jul 1, 2011

I am not a smart AC guy by I think my truck has great AC and is one of the better vehicles I have been around for AC perfomance so I think you are on the right track.

zilla68 · Jul 1, 2011

Poon said:
Last year my A/C had a leak in compressor, so I replaced comp, dryer, and oriface tube, charged it up and it was cool but never really got cold. After that I took it to 3 different shops and they all said "that just as cold as this big old truck will get with the temps in the 90's here". Since then I have replaced oriface tube with the severe service one, did the ball valve heater core bypass, and took the evaporator core out and cleaned it ( it did need cleaning). Blender door and fresh air door are working properly. After the recharge it was a little better but no big improvement, temps coming out at around the 60 deg range. I got tired of their answers to my luke warm air so I broke down and bought some gauges yesterday and here's what I have come up with.

At idle my pressures were 38 low side and 200 on the high side.
at 2000 RPM the low side would drop to 29 and the high side would also drop down to just over 150.

The only knowledge I have of A/C work is from reading on forums. I'm thinking this means bad compressor. Let me know if anyone thinks I'm wrong before I spend the money on another new one. Thanks

where did you get the compressor from? mine was similar and new compressor and switches on the dash fixed it.

Poon · Jul 1, 2011

Copm came from Bumper to Bumper

chromehound · Jul 1, 2011

Man I'd kill for temps out of the vent at close to 60.

Going to be keeping an eye on your thread since I'm having A/C issues along those lines.

Talyn · Jul 2, 2011

The high side and low side pressures seem about right.
I'm not sure what they are supposed to be though.

I'm only guessing you know how to use manifold gauges properly though.

The reason your system is probably not performing properly is because a vacuum is not being drawn on it before more coolant is being put back in.

If you do not draw a vacuum, the system will never perform right.

bbbxcursion · Jul 2, 2011

Should be real cold with pressures like that.

DIE5EL · Jul 2, 2011

I always keep my bluepoint temp gauge in vent all the time. I also have a crew cab. Far as i know everything is working good. The coldest i've seen it was at 59-60*. I know that's Duct temp but i thought it was pretty good. Average of 85-90 degree days and 80-90% humidity. (sp?). I'm happy with it but want more. I just got to remember that its an Air conditioner not a refrigerator.

Dzchey21 · Jul 2, 2011

I have a temp Guages in my vent too and most of the time my temps are around 40-45 degrees seems like no matter how hot outside Wot like that range pretty well just cycles the compressor more.

Did you look into the temp probe in the evaporator? I have seen them on equipment where they will short cycle the compressor because the switch is fualty.

Alot of cat equipment I work on is almost always below 40 degrees out of the vent. Also cat says to.check pressures at 1400 rpms and they also say to close the doors and let the temps stabilize for 10 minutes

ActionRick · Jul 2, 2011

My book says:
LOW side 24-47
HIGH side 128-230

TyCorr · Jul 2, 2011

Mine isnt real cold either and I think mine has more to do with my vacuum system not working properly. Sometimes when it rains and the short causes the vacuum pump to work the air that comes out of my vents is FREEZING cold.

To the op-you could have moisture trapped in your a/c and its not allowing it to work properly.

Jake · Jul 2, 2011

The two lines that run in and out of the core should have about a 30deg differential. So 60 deg air with 90deg outside is about right. Will it not get below 60 with it on max ac?

Talyn · Jul 3, 2011

ActionRick said:
My book says:
LOW side 24-47
HIGH side 128-230

WTH.
Its giving that big of a difference Rick?
Thats crazy.

TyCorr · Jul 3, 2011

Ive seen my low side higher than that when its 100 deg outside. Seen it up around 60psi.

zilla68 · Jul 3, 2011

I checked mine yesterday at the vent was right at 40 degrees, after I did the ranger mod, it was about 45is before.

look really close at your door, I thought mine was "ok" also, but it was losing vacuum at the switches, replaced those and all is well.

Talyn · Jul 5, 2011

Yeah, its very easy to loose vacuum behind the switches.
Just a crappy piece of rubber back there.
If one of the tabs breaks, or it comes loose..

bad design all around.
it works, but its a bad design.

Poon · Jul 5, 2011

Jake said:
The two lines that run in and out of the core should have about a 30deg differential. So 60 deg air with 90deg outside is about right. Will it not get below 60 with it on max ac?

Yes. Not below 60 on Max. I'm Putting new comp on tonight and having it charged tomorrow, then I'm going to check that blender door to make sure it isn't leaking down. Any idea on how to get a good look at the blender door? I saw it through the heater core cover when i checked it. Any other way to keep an eye on it for movement?

zilla68 · Jul 5, 2011

not really, I was so pissed at mine because the temps were right where yours were, so I thought hell, I replaced everything but the switches, might as well do those.

I pulled the panel off the dash, and even though it had never been off before, it wasn't holding pressure. I pulled the vacuum lines loose and stuck a mighty vac tool and found out that way.

You might have someone inside the truck with it running, and your on the passenger side under the hood, right by the hinge, and watch the vacuum module when they switch to max a/c and see when it activates and if its holding. Mine wouldn't pull all the way in, and after the new switches, that thing would suck a golf ball thru a garden hose! I bought mine from partsguyed.com for like 50 bucks I think it was, for all of them, but I didn't replace one of them. I think I replaced the middle and the right IIRC

Poon · Jul 8, 2011

I put on new compressor, had it vaced and charged. Now my temps are blowing out at 46. That is a great improvement over what it was. As far as the hot/cold blender door, it is run by a cable , not vacuum. The heater core bypass is working. I pulled the heater core box apart after 30 mins of driving and it was stone cold. I checked the fresh air blender door and it was closed sitting at idle, but I had no way to check it while moving so I zip tied it closed for testing purposes. Like I said, after 30 mins of driving the temps were around 46, But i got home, left the truck running on high idle in the driveway for about 10 mins and when I came out the thermometer said 40 degs. I thought the temps would be lower driving down the road than sitting still. Any idea ? If it will be that cold with no air movement, then I want it that cold driving.

zilla68 · Jul 8, 2011

my door is not run by a cable, its vac, that is the actuator under the hood on passenger side on top of the fan box.
I know when I watched mine you can see the actuator move as you turn the knob in the cab to max ac
46 is really good, maybe you saw 40 because there is no load on the motor, its just sitting on high idle, don't know.