2nd Gen Non-Engine/Transmission Here is the ac readings

[SAndreasen]

Here is what the gauge reads on the ac system truck is running clutch engaged

 

[SAndreasen]

Clutch disengaged

 

[SAndreasen]

Low side reads 30 with clutch on and high side reads 50

 

[fest3er]

A non-professional observation:

The high side should be a good deal higher than that, perhaps at least 150PSI.

If the system is charge exactly to spec, you should see the low side slowly drop to around 23PSI where the clutch disengages (the compressor has sucked its intake 'dry') and a little more quickly rise to around 45PSI where the clutch re-engages. This is, of course, dependent on ambient temp; it will cycle more quickly when cold and more slowly when hot.

If you add more R134, you'll probably find the clutch does not disengage on a hot day; the low side pressure will hover somewhere between ~30 and ~45 PSI.

I found that *3* ounces extra makes the A/C pleasantly frigid on scorching hot days on the highway and cool enough around town. But it also makes the A/C fail to dry the air enough when the temp is under~ 40°F because it cycles *too* quickly. Thus the windows frog up more in the winter.

 

[SAndreasen]

According to what I've found reading my ac training manual it looks to be the expansion valve is the culprit ? Anybody agree disagree

 

[B.G. Smith]

Looks like you have the pictures cross identified. With an outside temp. around 75/80 deg.F you should have about 130# on the high side with nothing running. Wish I could help but don't have the answer. bg

 

[B.G. Smith]

If the unit is fully charged and the metering orifice is plugged you should get condensing pressure on the high side until the compressor cycles off. Condensing pressure would be according to outside temp. plus several pounds for heat of compression and depending on air flow to condenser. bg

 

[SAndreasen]

If the unit is fully charged and the metering orifice is plugged you should get condensing pressure on the high side until the compressor cycles off. Condensing pressure would be according to outside temp. plus several pounds for heat of compression and depending on air flow to condenser. bg

Only psi on the high side is 48 psi drops down with compressor off and the low will go to about 60 psi with compressor off . Compressor on drops low to around 24 - 30 high side goes up to 48 psi with compressor on . I guess I will start throwing parts at it because that's what the reputable shop is doing and for the 600 I've already spent I almost could have replaced the whole system

 

[B.G. Smith]

With those pressures, either there is not a full charge in unit or there is some refrigerant other than R-134A in it. Of course the pressures could be low because the outside temperature is 35 or 40 degrees but I doubt that is the case or you wouldn't be trying to fix the system. .bg

 

[SAndreasen]

The low side pressure is 60 pounds with a static system everything I've found shows that to be about right or even a little high

 

[SAndreasen]

Ok my book says 150 on the high side at 80 degrees I had 48 psi on the high side at 72 degrees. It also says the low side should read 30 psi , so why am I 100 psi low on the high side ? I would say maybe a bad gauge but the system doesn't cool right so something isn't right somewhere . When I ran the power probe to power the clutch I could get cold air the high side pressure gauge went even lower at this time after running the system like this for maybe five minutes I should also add that I had the truck rpm set at about 1800 - 2000.

 

[B.G. Smith]

Look at it like this. The air conditioner refrigerant is a closed loop. No check valves except in the compressor which keeps the refrigerant from flowing backward.(except in a scroll type compressor) I don't know what type metering valve your system has but I think it is an orifice with a screen ahead of it to hopefully keep it from becoming plugged or restricted. Even if it is an expansion valve, the pressures from discharge to suction pretty much equalizes when the system is off Ok, the outside temperature is 72 deg F, the pressure in the system should be around 75 pounds. The system holds about 32 ounces, why don't you remove what is in the system (yes I know it is illegal to discharge refrigerant into the atmosphere) and put in two 14 oz. cans and see what happens? That will be a lot less money than an hours labor at the shop. bg

 

[DavidC]

Kinda sounds like the orifice valve is at least partially restricted.

Dave

 

[DavidC]

Dave

 

[Tuesdak]

Are you 100% sure the low side is higher with the truck running?! Otherwise the pictures are backwards.

If it's 30 PSI low and 50 PSI high with the compressor running you could have a massive leak and very low system charge.

The blower is on high, correct?

What do the lines into the evaporator look and feel like? Is one to the accumulator warm and the other one ice?

If the low side rises with the compressor on there is a restriction past the low side service port.

First be sure the system charge is correct. I would have it sucked down at another shop and note the weight that is recovered. If the recovered charge is within 1/4 LB you have a restriction in the system aside of the orface tube. Accumulator and hoses are suspect for restrictions. Rare but a restricted (from debris) or internally corroded evaporator are possible.

If the charge is low do a vacuum test. (See if it holds being pulled down 15 min and then keeps the same vacuum reading for 15 min. Loosing vacuum indicates a leak)

Is there any ice lines showing up on the hoses? Ice at a specific point can be a restriction.

 

[mweiman]

You mentioned that you have spent money with a shop to work on it. Any idea what they have done to it? Your guage readings don't indicate a plugged orifice tube if it is fully charged. You would have very high high side readings and low side low or even into a vacuum. To me it seems like low charge without knowing any history of repairs. Not real likely but possible to have the orifice tube stuck open.

 

[SAndreasen]

The shop replaced the compressor and supposedly fixed it . The system worked for about 30 minutes on the way home. And now sometimes will work for about 5 minutes all for about 600$ I had bought one compressor and replaced it but it had a bad clutch so carquest gave me a new one I also replaced the dryer what the shop did I don't know beside swap compressors and add dye and recharge the system . I hate to give them more and more money for a system they can't fix I can do that myself for free . This all stemmed from an accident I had in a field when I ran a piece of pipe through the condensor and blew all the refrigerant and oil I didn't even think to unplug the compressor and I think that's what ruined the original compressor .

 

[SAndreasen]

As far as the system not bieng charged is not 60 lbs the max charge you want ? My Chevy system tests at 60 pounds using the same set of gauges on the same day the system on it works blows super cold the dodge doesn't work

 

[madmanmanick]

From my experience, The A/C readings you showed in the pictures indicate to me that either your compressor is not engaging, or it is drastcally low in charge. Now you have said that you had a shop replace the compressor, then you changed it. Did you add any refrigerant oil to it when you did the repairs? If you didn't put any oil in the system it will not function right. What I would recommend doing is to buy, rent, or borrow a refrigerant vacuum pump and put the entire system under a deep vacuum(as close to 29" to 30" as possible). Then let the system sit for about 10 to 15 minutes and see if the pressure rises. That will indicate a system leak. If it leaks tighten all fittings, replace seals accordingly and test it again. Once the pressure stops rising then add one can of oil charge followed by the correct refrigerant charge. Best way to do that with the gauge set you have is too hook up the refrigerant bottles to the main yellow hose and hook it up to the connection with the shrader valve. Than get a separate bottle tap and shorter hose and attach it to the connection without the shrader valve. Once the oil charge is in close the bottle tap valve and then open the refrigerant bottle tap valve and charge the refrigerant. This will both clear your lines and ensure all the oil gets in the system. Charge the system to normal level and see what happens, this should fix it. Hope this helps.

 

[SAndreasen]

Thinking about just trading the whole thing off my buddy has a ford and his ac works why won't mine