AC Troubleshooting

[Matthew Jeschke]

A few years ago I had my decedent can break inside the dryer and throw little decedent balls all over the system. The orifice tube and expansion valves caught most all of it. Then I extensively cleaned the system with starter fluid, brake cleaner, and compressed air. I pulled the compressor and made sure nothing was inside of it (as best I could). Then I replaced all the o-rings, expansion valve and orifice tube.

The AC started acting up again before I blew my motor. It was intermittent and beginning to blow less cool air. Also the clutch would turn off and on for the AC. Well it's HOT here now and I want AC haha I went to charge the system now that my engine is rebuild and I think I found the issue from before, there was a leak in the suction / dischargeline going from condenser to compressor.

I replaced that line and now when I charge it, the low side pressure is too high. I think? What should static pressure be? I don't know... When compressor is not running static pressure is around 70PSI. What should my static pressures be? I'm not really sure? No manuals say...

The compressor does seem to make a noise. Video of everything HERE:

https://drive.google.com/file/d/1wRGZsI4ozbYjbA8zFZPF8Cfe4tIeqfip/view?usp=sharing

Also it's a Denzo compressor takes PAG46 and truck has rear air. I see LOTS of options to buy compressors. However, confused as to which ones are which.

I know enough about auto AC to be dangerous haha.

 

[Dantheman1540]

Static pressure at 70 doesn't seem crazy but static isn't really important.

You can't get the compressor to come on at all? Do you have a full set of gauges?


I've had a bunch of AC trouble over that last 2 years. I'm not a pro but I like to think I've learned a little.

 

[ks03]

Static pressure is a function of temperature. About 70psi is normal for a vehicle that has been sitting parked with an ambient temperature about 70*F
https://ricksfreeautorepairadvice.c...34a-pressure-temperature-chart-2-650x1024.jpg

…it tells you little about how much 134a is in the system

 

[Matthew Jeschke]

My problem is I get all nervous when I do this because any little mistake means I loose $30 of refrigerant haha. I have full gauges and bought a vacuum pump as well. Got tired of rentals not being reliable.

I gathered the courage to dump 2 1/2 more cans of refrigerant in. The pressures came more in check. I think I got nervous and overthought it when I started hearing weird noises, the pump cycled on and off, and I saw 70 PSI when compressor disengaged.

Ambient temperature is 100F in my garage.

• I'm now at 55 to 56 PSI low side, 300ish PSI high side.
• Compressor stays on.
• I turn the truck off it settles down to 100PSI or so both sides.
• I listen with my mechanics stethoscope I don't get the weird noises anymore from the compressor when it's running anymore.
• Only thing is pressure chart says I should be at more like 330 PSI high side.
• I'm getting around 40F on inside of front middle vent and on rear air vents.

Thanks for the help

I wonder if I need a tinge more refrigerant despite low side is spot on? Or if that's a sign my compressor is a bit tired and old?

Thanks for correlation on static pressure. So I'm at about 100PSI and it's 95F outside. So maybe I do need to add a bit more refrigerant? hrm...

I went for a test drive... Going down highway it damn near freezes me out. When I'm driving city streets it's okay. When I'm idling, it's well cool but not freezing.

 

[ks03]

My problem is I get all nervous when I do this because any little mistake means I loose $30 of refrigerant haha. I have full gauges and bought a vacuum pump as well. Got tired of rentals not being reliable.

I gathered the courage to dump 2 1/2 more cans of refrigerant in. The pressures came more in check. I think I got nervous and overthought it when I started hearing weird noises, the pump cycled on and off, and I saw 70 PSI when compressor disengaged.

Ambient temperature is 100F in my garage.

• I'm now at 55 to 56 PSI low side, 300ish PSI high side.
• Compressor stays on.
• I turn the truck off it settles down to 100PSI or so both sides.
• I listen with my mechanics stethoscope I don't get the weird noises anymore from the compressor when it's running anymore.
• Only thing is pressure chart says I should be at more like 330 PSI high side.
• I'm getting around 40F on inside of front middle vent and on rear air vents.

Thanks for the help

I wonder if I need a tinge more refrigerant despite low side is spot on? Or if that's a sign my compressor is a bit tired and old?

Thanks for correlation on static pressure. So I'm at about 100PSI and it's 95F outside. So maybe I do need to add a bit more refrigerant? hrm...

I went for a test drive... Going down highway it damn near freezes me out. When I'm driving city streets it's okay. When I'm idling, it's well cool but not freezing.

If it’s working well, don’t mess with it. Static pressure is about meaningless unless it’s wayyy high or low. To nail the charge amount you need very accurate scales (actual ac machine). So again, if it’s performing well, I’d let it be.
IIRC gm specs as little as a 30*F drop between ambient temp and vent discharge temp, but I think that’s at high humidity.

 

[ks03]

When I'm idling, it's well cool but not freezing.

I’m a big fan of electric fans, for idle ac performance.
Running the oe mechanical setup?

 

[exp500]

These moght help.

 

[Matthew Jeschke]

Awesome, so I am close I will call it good.

Yeah, I like electric fans too.... However I have had electric fail before. I use this truck for offroad so glad it is the water pump drive style.

Could it be a bad clutch on the fan though? Should it pull more air at idle to cool the condenser?

I fiddled with the clutch but not sure how to tell for sure.

Sent from my SM-A505U using Tapatalk

 

[Matthew Jeschke]

These moght help.

thanks for the charts I was searching for them. Very helpful.

Sent from my SM-A505U using Tapatalk

 

[ks03]

Awesome, so I am close I will call it good.

Yeah, I like electric fans too.... However I have had electric fail before. I use this truck for offroad so glad it is the water pump drive style.

Could it be a bad clutch on the fan though? Should it pull more air at idle to cool the condenser?

I fiddled with the clutch but not sure how to tell for sure.

Sent from my SM-A505U using Tapatalk

I thought my fan clutch was working properly, but electric improved ac performance at idle.
I haven’t done it, but if you wanted more, you could look into adding an electric pusher fan, even if it only covers part of the condenser it would help. Then you could keep your mechanical and the reliability of it, plus add additional cooling, which seems like a good thing off-roading in AZ

 

[Dantheman1540]

Electric fans are a massive improvement in AC performance! I was just tuning mine to come on sooner now that it's hot as fuhq out. I hate losing refrigerant too but buying the $3.99 cans at Harbour freight makes it not as bad.

Having a 100* ambient in the garage makes it difficult to tell if its working too. I had my fans on, and the truck idling in the shop but it still blew warm because it was so hot combine with a lack of fresh airflow. Go for a drive and cool the system down if it's exhibiting signs of the condenser not working well enough.

 

[Matthew Jeschke]

dang they are 4$ at harbor freight! wow, I was paying 5 to 7 dollars per 8 oz can.

Sent from my SM-A505U using Tapatalk

 

[R422b]

dang they are 4$ at harbor freight! wow, I was paying 5 to 7 dollars per 8 oz can.

Sent from my SM-A505U using Tapatalk

If you get your refrigerant license you can get a 30 lb tank for about $4 a pound and then you can accurately charge it with a scale.

talking about Chevy's using Tapatalk

 

[Matthew Jeschke]

I thought my fan clutch was working properly, but electric improved ac performance at idle.
I haven’t done it, but if you wanted more, you could look into adding an electric pusher fan, even if it only covers part of the condenser it would help. Then you could keep your mechanical and the reliability of it, plus add additional cooling, which seems like a good thing off-roading in AZ

Wow that's a cool idea! Never thought of that. Would be a good idea to increase the size of my transmission cooler and put a pusher on there... might get some added benefit with my AC too

If you get your refrigerant license you can get a 30 lb tank for about $4 a pound and then you can accurately charge it with a scale.

talking about Chevy's using Tapatalk

That would be cool. Kind of annoyed they won't sell the stuff to non-licensed people. I see quotes all over the place that R134a tetrafluoroethane is bad for the ozone layer... It's illegal to vent into atmosphere. Yet the other day I turned over my dust off container. It literally had tetrafluoroethane, r134a in it haha

Some of the others have difluoroethane in them or propane/butane. Too bad those are flammable. Otherwise I'd just charge up with them

 

[R422b]

Wow that's a cool idea! Never thought of that. Would be a good idea to increase the size of my transmission cooler and put a pusher on there... might get some added benefit with my AC too



That would be cool. Kind of annoyed they won't sell the stuff to non-licensed people. I see quotes all over the place that R134a tetrafluoroethane is bad for the ozone layer... It's illegal to vent into atmosphere. Yet the other day I turned over my dust off container. It literally had tetrafluoroethane, r134a in it haha

Some of the others have difluoroethane in them or propane/butane. Too bad those are flammable. Otherwise I'd just charge up with them

The license is literally $25 and an open book test. You pretty much can't fail. I got mine through MACS https://macsmobileairclimate.org/
The free license manual is really good and I learned a few things from it.
r134a is not bad for the ozone but it is a "greenhouse gas" so you are legally not allowed to vent it.

talking about Chevy's using Tapatalk