AC Problems. R132 present, Clutch Turning, Hot Air.

[DavidC]

The flush is used after a compressor failure or debris (such as internal hose decay etc. that is in the system). A drier is required for warranty on a compressor change. Most suggest replacing drier if the system is opened to atmosphere. If the orifice is plugged the complete line is replaced. When all connections are done a vacuum needs to be done to burn off air in the system, check for leaks and ready the system for freon. I would really make sure your freon charge is good before going to far. If a flush happens you need to also put some correct pag oil to replace what was coating the system which can be a pain if you do not drain the compressor and measure the volume. It can get to be a very intense project. Too much/not enough oil can cause problems just like 134A. The old R12 days were a lot kinder. When/if i add freon i usually jumper the low pressure switch to keep the clutch engaged while watching pressures.

Dave

 

[glmoore001]

The flush is used after a compressor failure or debris (such as internal hose decay etc. that is in the system). A drier is required for warranty on a compressor change. Most suggest replacing drier if the system is opened to atmosphere.
Dave

I have no idea what has happened with the truck in the past. I purchased it on the West coast in April. The compessor could have blown and I wouldn't know it.
I will need to have the unit drawn down, otherwise I will not know how much refrigerant to add.
Any problems in your experience replacing the dryers? Did everything come apart and reconnect without problems?
Thanks Gary

 

[DavidC]

I have no idea what has happened with the truck in the past. I purchased it on the West coast in April. I will need to have the unit drawn down, otherwise I will not know how much refrigerant to add.
Any problems in your experience replacing the dryers? Did everything come apart and reconnect without problems?
Thanks Gary

No problems. Just have new o-rings, tool for the lines and pag oil to lube the rings/connections. Stock up on patience as any connection point can get frustrating taking apart. Usually goes together ok.

Dave

 

[Wayne M.]

If you want to do any forensic work, you can just rip out the liquid line and cut out the orfice tube. Usually there's a screen built into that, and if your compressor did puke, you'll see evidence there. But of course, you'll be commited to change it.

 

[DavidC]

If you want to do any forensic work, you can just rip out the liquid line and cut out the orfice tube. Usually there's a screen built into that, and if your compressor did puke, you'll see evidence there. But of course, you'll be commited to change it.

You would think (maybe there is) a way to install a removable Valve by now without changing the whole line.

Dave

 

[fest3er]

What do I remember from changing my evap and accumulator.... (Were the A/C or fuel line connections rusted to destruction? Fuel, I think.) IIRC, the A/C connections came apart fairly easily, though I might've needed a bit of volatile lube to loosen them. The hardest part was removing/installing the dashboard (which has been disintegrating since). I installed the new evap and accumulator, then brought the truck to a shop where the system was evacuated, tested, then filled (with I think 1-2 extra ounces of R134). He added enough lube to handle the new evap and accumulator. It works better now than it did during its first 15 years of life.

Pulling the vacuum does two things. First, it evaporates any water that's gotten into the system while open. Second, it tests for leaks (if the vacuum doesn't hold for 20 minutes, something's leaking.)

 

[glmoore001]

I am going to have to replace my dashtop also, will do both the evap and heater coil when that time comes, have no plans to do it now though.

 

[glmoore001]

No problems. Just have new o-rings, tool for the lines and pag oil to lube the rings/connections. Stock up on patience as any connection point can get frustrating taking apart. Usually goes together ok.
Dave

So when you say a tool for the lines, you are talking line wrenches, right?
The line you are talking about with the orifice runs by the passenger side fender to the firewall, correct?

thanks to all the contributors.. I really appreciate the help... Gary

 

[DavidC]

Usually everyone has wrenches. It is those spring clamp tools to have a set of.
https://smile.amazon.com/OEMTOOLS-25184-Spring-Lock-Coupling/dp/B0014WK8JG

#ad

Dave

 

[B.G. Smith]

B.G. Smith, you might be on to something here. My recovery station has those quick couplers with the integrated valves. To open the valves requires turning the knob the opposite direction than you would think - clockwise to open. Once when I was testing a system before recovering the refrigerant, I had the valves closed (thought I had them open). Both high and low pressures read about the same and the AC clutch was cycling. Hmmm... After a few minutes I figured out my error and things began working normally.

So, if this is what is going on for the OP, it could explain his symptoms, and really, he just may have a low charge.

- John

Yes, something strange is going on, if the clutch is cycling then the suction pressure is going up and down? bg

 

[DavidC]

Yes, something strange is going on, if the clutch is cycling then the suction pressure is going up and down? bg

Yes, that is why I kind of asked that earlier. If the clutch is cycling then the low pressure switch would appear to be working which should show on the gauges.

Dave

 

[y2k17ram]

Check the fins on your radiator (plugged?) - could be airflow

 

[glmoore001]

Usually everyone has wrenches. It is those spring clamp tools to have a set of.
https://smile.amazon.com/OEMTOOLS-25184-Spring-Lock-Coupling/dp/B0014WK8JG

#ad

Dave

So, these are needed to replace the lines on our trucks?
Thanks.. Gary

 

[glmoore001]

Yes, that is why I kind of asked that earlier. If the clutch is cycling then the low pressure switch would appear to be working which should show on the gauges.

Dave

Maybe the compressor is not turning at all even though the clutch is cycling.
I will dig into it s little more on Friday, we are supposed to get some nice weather again.. Gary

 

[glmoore001]

(1) Confirm that the refrigerant system is properly
charged. See Refrigerant System Charge in the Service
Procedures section of this group.
(2) Start the engine. Turn on the air conditioning
system and confirm that the compressor clutch is
engaged.
(3) Allow the air conditioning system to operate for
five minutes.
(4) Lightly and cautiously touch the liquid line
near the condenser outlet at the front of the engine
compartment. The liquid line should be hot to the
touch.
(5) Touch the liquid line near the evaporator inlet
at the rear of the engine compartment. The liquid
line should be cold to the touch.
(6) If there is a distinct temperature differential
between the two ends of the liquid line, the orifice
tube is in good condition. If there is little or no
detectable temperature differential between the two
ends of the liquid line, the orifice tube is obstructed
or missing and the liquid line must be replaced

Dave

Minutes ago.... I had run the a/c for nearly a half hour, pulled into the drive, made sure the compressor was cycling (it was), checked the line coming out of the condensor and it was very warm, not hot. I then checked the line near the low pressure inlet at the firewall and it was cold. Not freezing cold, but cold enough that it had condensed water well formed on it.
The fan inside the cabin blew lukewarm air. Air temp outside was 78 degrees.
I will do some thorough checks come friday, maybe put in some refrigerant and dye and see what happens..
Thanks.. Gary

 

[DavidC]

My leaks have been the low schrader Valve. One time was the High pressure ball valve. Sometimes just tightening the schrader solves the problem. A good freon sniiffer is good to have for those things.

Dave

 

[fest3er]

Minutes ago.... I had run the a/c for nearly a half hour, pulled into the drive, made sure the compressor was cycling (it was), checked the line coming out of the condensor and it was very warm, not hot. I then checked the line near the low pressure inlet at the firewall and it was cold. Not freezing cold, but cold enough that it had condensed water well formed on it.
The fan inside the cabin blew lukewarm air. Air temp outside was 78 degrees.
I will do some thorough checks come friday, maybe put in some refrigerant and dye and see what happens..
Thanks.. Gary

Add one can of r134a (and add dye). If it gets cooler, the compressor is probably OK and you should use a UV light to look for leaks. I suspect the clutch is cycling fairly rapidly (on the order of 3-5 seconds). Adding one can might slow the cycling to 10-15 seconds. As a rule-of-thumb, the clutch really shouldn't cycle more than around every minute or three. The cycle time does depend on ambient air temp and how well the whole system rejects heat from the condensor*. If you put too much r134a in, it'll never draw the low pressure down low enough for the low pressure switch to open; the compressor will always run (as did those in Dodges/Plymouths in the late '60s and early '70s).

In my case, there was a tiny bit of flourescense by the condensate drain and almost none anywhere else. The evap had a leak, but was slow enough that it wasn't apparent until I removed it; the dye just didn't migrate very far.

The compressor compresses the gas; this adds lots of energy (heat). The gas then passes through the condensor which, if it works well, removes that heat and allows the hot gas to condense into liquid. This liquid then flows to the evaporator behind the dash where it passes through an orifice that allows the liquid to evaporate and get really cold. The gas then absorbs heat from the cabin (or from fresh air entering the cabin) and then returns to the compressor to be squashed into a high pressure gas. And the cycle continues. With the *right* amount of r134a, the system will cool and dry air significantly below freezing (32°F, 0°C), thus helping to defrost your windows in the winter, yet still cool the cabin up to maybe 100°F ambient.

If you replace parts, be sure to lube the connection parts with r134a oil. They'll go together easier and the oil may help slow down corrosion on the atmosphere side of the joints. (No, no, don't soak your papers in the oil; this is probably contra-indicated.)

 

[glmoore001]

Add one can of r134a (and add dye). If it gets cooler, the compressor is probably OK and you should use a UV light to look for leaks. I suspect the clutch is cycling fairly rapidly (on the order of 3-5 seconds). Adding one can might slow the cycling to 10-15 seconds. As a rule-of-thumb, the clutch really shouldn't cycle more than around every minute or three. The cycle time does depend on ambient air temp and how well the whole system rejects heat from the condensor*. If you put too much r134a in, it'll never draw the low pressure down low enough for the low pressure switch to open; the compressor will always run (as did those in Dodges/Plymouths in the late '60s and early '70s).

Ok, I will give it a try this evening or friday am. Thank you for the explanation of how the system works, that was very helpful.. Gary

 

[glmoore001]

Hooked up the gauges, put some dye in the charge tube, hooked up a small can of refrigerant, turned on the ac, started the engine and opened the low side valve. The thermometer was reading 100 degrees from being in the sun when I first turned on the fan, as it was filling, I looked at temp, down to 65. Back to gauges, gauges were cycling, Looked at the low side 45 psi high side 415 psi!
Eek!!!! I shut it off.

 

[glmoore001]

I waited a while, put the gauges back on and started the truck. High side down to 275, low at 25, compressor not cycling at all, runs continuously. Static pressure on both sides about 110.