A/C Pressure Question

[goreje]

I didn’t see a forum for A/C questions/topics, so I’m posting here. If in the wrong spot, please move.

Back story before leaving on vacation 6/7, A/C ran fine when parked in driveway.

Returned on 6/15, moved truck to rearrange vehicles on our return, and A/C is blowing warm air at best.

Air flow is fine but luke warm to warm.

2018 Ram 3500, 6.7 Cummins, engine is bone stock.

Hadn’t done any mechanical work to it.

This week, driving it, I noticed I wasn’t hearing the fan clutch engage like before.

Today, I picked up a set of gauges to check pressures.

While getting the hoses hooked to the manifold, I had the truck at high idle (1,500 RPM) and finally started hearing the fan clutch engage.

Engine at operating temp (192-195), A/C on max and recirculate, temp set to low, doors/windows open I got the below gauge readings.

I’m definitely NOT an A/C guy, but my assumption is, I have a faulty compressor.

Low Pressure - 42psi
High Pressure - 45psi

Y’all’s thoughts?

Compressor and more? Compressor and fan clutch going out/weak?

IMG_7186.jpg


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[goreje]

To add to the information, I brought the truck back to an idle (750ish rpm), and low pressure rose to roughly 110 psi and was climbing still.

High pressure stayed steady at 45-50 psi.

The temperature outside was 85-90F.


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[AK Bob]

To add to the information, I brought the truck back to an idle (750ish rpm), and low pressure rose to roughly 110 psi and was climbing still.

High pressure stayed steady at 45-50 psi.

The temperature outside was 85-90F.


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See attached AC Performance troubleshooting information.

Could be low refrigerant charge, refrigerant flow throu A/C evaporator restricted, or the compressor.

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[goreje]

@AK Bob Thank you, Sir.

I’ll look this over this week and see what I can get done this weekend.


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[AK Bob]

@AK Bob; Thank you, Sir.

I’ll look this over this week and see what I can get done this weekend.

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You are welcome.

Please keep us posted on your progress.

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[sootmaster]

Hello, ensure the clutch has been applied and engaged with low-hi sides; both seem the same.

I would turn off the engine and on the compressor clutch rotate by hand if you feel no resistance, then either the shaft has broken or the squash plate inside is broken.

Suppose the compressor has internally generated metal from grinding.

In that case, you will have to flush and replace the face tube or expansion block accumulator compressor, flush all lines EVAP and condenser refill with oil, drain out whatever is in the compressor, and turn to make sure empty you are filling will rest assure proper amount and not over oil charge AC system.

With the Low Blue gauge raising, the hose may be backward on the gauge set.

The red gauge hi side goes to the larger port valve and port near the condenser front of the truck.

Blue gauge is a smaller hose valve near the accum of the firewall.

The hoses on the gauge set are the same and can be placed in either position, just FYI.

Either way, only building 110ish is low for AC functions at your temp outside.

RECIR- Normal is Low 30psi and 210-275 + - hi side.

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[goreje]

@sootmaster Yes, Sir.

Blue coupling to blue hose to blue gauge coupled to low side (suction port).

Red coupling to red hose to red gauge coupled to high side (discharge port).

Below are a couple of photos from this evening.

Fill/evac line (yellow hose) didn’t have a seal on one end the other day after the picture I took. I guess it fell out, so I had to return the gauges.

Temp: 89F
Humidity: 68%
Apparent (feels like) temp: 98F

IMG_7214.jpg

IMG_7206.jpg

Vent temp did get cooler, but, obviously, by gauge readings, not operating correctly.

This weekend I’ll take the belt off and check the compressor pulley and belt tensioner and the rest of the pulleys while that deep into it.

Edit: I'm not sure if photos uploaded.

These were taken while adding about 2.4-2.5 scale was flickering back and forth.

First (compressor cycled on)- low was at 35psi, high at 125psi.

Second (cycled off) - low at 70psi, high at 130psi

After the small charge for what was lost yesterday and the yellow hose hooked back up to check pressures (no picture taken) low was at a steady 20psi, high was at a steady 85-90 psi.

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[sootmaster]

Hello, the pressures you updated are so different!

Low Is Pulling down, and Hi Side is showing rising good now; if the readings are steady when cycling on, that's a plus.

I suspect you are low on refrigerant.

I CAUTION the use of Quick Freon you get at the (Auto Zone, etc.) parts stores as the EPA Big Brother has the manufacturer to ADD AC SEALANT to the mix!!

NOW, in time, this sealer becomes separated and forms a gum in the entire AC system, requiring the replacement of ALL these components.

May Due to the Fan clutch or HI pressure, it discharged out the relief valve on the compressor.

It is a little brass-looking valve; look for green dye at this valve.

If you have UV Light or UV-Flash light, look around for dye traces.

Harbor Freight may have a little kit, as it seems anything in China they have!

Rock Chip in the condenser can cause leakage, but it seems with your present system pressure like a crimp, line, or discharged out valve.

In your inspection, were the caps on the port valve wet with oil?

This would confirm Charge port valves.

A few quick things will be inspections, as small leaks are time-consuming to verify.

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[goreje]

Refrigerant added was just refrigerant.

No oils or leak stop/sealers (or at least so it says).

Harbor Freight (SKU: 57193).

A rock chip in the condenser may be the culprit.

I have (the best I could see through the grille and from above) about a softball-sized oily spot on the condenser.

HI & LOW ports were clean/dry with no oily residue.

The low side took so doing to see into.

I'll know more this weekend.

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[sootmaster]

Any oils on condenser would be a failure as this is washed with rain.

Sounds like you found it!

Can confirm with cheap uv light.

Way better then evaporator behind dash.

Vacuum is very important to remove moisture from new part and being exposed to air.

At least 30-1hr add 2oz oil unsure if equipment with dyer on core?



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