Where is the dash air conditioning service port?

[Stan Simpson]

Update:

After finally finding the service ports for the air conditioning on my C-9. I went to O'Relley's and bought the AC Pro that Bill Sprague used. They gave me a tutorial on how to recognize the correct schrader valve no matter what color the cap. The high pressure one is shorter and fatter than the low pressure (the one I wanted) which is taller and skinnier. Also, the fill nozzle will not fit on the wrong valve. Turns out my high pressure one had a red cap, and was pretty visible on the top of the engine just above the compressor clutch/pulley assembly. There are a plethora of hoses and lines going across that area, so I finally got a little step stool and stood on it while I searched among them for a second cap which everyone said had to be close to the red one. After forcing some lines out of the way (careful not to break or disconnect anything) I finally felt another cap like the red one. I unscrewed it and it was black. However, it WAS from the low pressure port. The guy at O'Reilley's said it likely had been replaced at some point.

Even with the long hose on the fill nozzle of the refrigerant can, it took me a long time to connect it to the schrader valve. There were just so many things in the way, and at no time could I actually see it. It was all by feel. So, I followed the instructions, turning the air on the dash to full blast. I dialed in the ambient temperature as instructed.

Not good after that point.

The clutch on the a/c never engaged. Could it be because the ambient temperature was only 54 degrees? The lowest temperature to dial on the gauge was 75. I squeezed the trigger once to see what happened, and the gauge immediately went into the red. I unplugged everything, and am back to square one. Could there be a problem with the a/c clutch? I don't recall it not coming on before. Is there a chance it will work better if the temperature is above 75?

It appears that my serpentine belt is okay. No cracks that I could see.

Any ideas would be appreciated.

Stan

[Edward Buker]

Stan,

Usually when the clutch won't come on it is because the pressure is below where the pressure sensor allows the compressor to run due to low refrigerant. As long as the pressure started out below the recommended level you should be fine. You need to get a temp for charging that is on the scale so that you have a calibrated charge. If it is 54 degrees and you use 74 degrees on the scale you will have over charged.

It is normal for the gauge to go high as you add some charge given the compressor is not pulling in the R134a and is stopped. It is a slow process but you can hit the trigger intermittently and then let the pressure decrease a bit and then hit it again and the compressor should eventually come on once enough pressure is in the system. The low side pressure will equalize with the high side pressure with the compressor off but it is a slow process due to a small orifice in the path. Once the compressor comes on you will still see increases on the gauge as you add but the reading will settle to the true system operating value in a few seconds with the trigger released.

With the compressor off you are basically trying to fill the system through a very small hole until the compressor engages.

Later Ed

[Stan Simpson]

Thank you so much, Ed. I'm doggedly determined to learn these things, but I will never, at my age - 66, learn what you and others on this forum seemingly have at your fingertips. I salute all of you. I spent my entire working career as a pencil pusher, and  although when I was younger I changed my own oil and filters, that is the extent of my knowledge over the years. I do understand the principal of an internal combustion engine but have little practical hands on experience.

I will be back at it as soon as it gets warmer! We're leaving Thursday for a leisurely trip to Gillette by the 14th.

Thanks again!

Stan

[Edward Buker]

Stan,

From the existing gauge calibration you should be able to rough estimate where 55-60 degree needle location would be and that would be close enough if you wanted to give it another try before Gillette. At Gillette you could probably get a hand from someone if you do not get to it before then...we only learn by doing and I was a pencil pusher also but I always liked working with my hands. I'm 64 and things do not stay with me like they used to...

Determination is a good thing, just be careful and you should be fine.

Later Ed

[Andy Clark]

Good info, Ed. Thanks.

I'm having a problem with my dash air also: I have a set of dual gauges and know where to connect them. The low side port at the compressor has a defective Schrader valve so that I cannot fill there. AHA!!, but Beaver added another low side port at the evaporator housing behind the removable panel in the nose of the coach, so I fill from there.
However, here's the issue: the low pressure switch will not let the compressor start. With the compressor jumped straight to the batt and running I cannot get the high-side pressure anywhere near the 220psi (or so) level, and the low side pressure goes up a bit then settles back down to around 15-20psi no matter how much R134 I add. Then when I shut the system down, the low and high sides take about 3hours to equalize. I've been told this is not normal and both symptoms could be caused by a partially plugged orifice (the small one you metioned).
What say you?
Andy

[Edward Buker]

Andy,

There is usually a screen leading to the expansion valve that may be plugged. Most likely source is a bag of desiccant in the receiver dryer might have broke. This is really a guess. The expansion valve may also be a culprit here. The fact that you cannot get the pressure up indicates that the compressor may be bad or a blockage keeps it from having available R134A at the suction side. You could talk to a local air shop and see what they would do if you brought it in. If you have to break into the system you would need some new Orings, a vacuum pump to evacuate the system, an new receiver drier, replace the Schrader valve, probably a new expansion valve and flush and clean the screen and piping from the drier if you have desiccant in the screen. This is deeper than I have had to go in repairs so I am offering a semi educated guess. As with all these things you have to decide where your skills end and a good shop's skills is required.

Later Ed

[Andy Clark]

Thanks, Ed. I have the equipment to pump down and fully charge the A/C system, but not what's required to pump out and collect the R-134 that's in there. I cannot, in good conscience, vent it to the air, even tho' it's less damaging to the environment than the old R-12, so, it looks like A/C shop time is in order.
Thanks again.
Andy

[Edward Buker]

Andy,

Good luck with it. You should be able to find a reputable shop near home. I like having things like this done near home in case the repair does not hold up. If you have collected that equipment then you are in good shape to provide the right info to the repair shop. Enjoy your summer and travels.

Later Ed