Dash AC

[Richard and Rhonda]

There's been a lot of off forum talk about the dash AC this week.

I don't know if these numbers will help you, but I checked mine tonight.

Ambient was 95 degrees. Air at the discharge vent was 61. 34 degrees is about as good as I think you can reasonably expect. Temp inside the coach was about 85 when I did this.

Low side with engine on high idle was 20 to 25 psig, and high side was 325 psig.

I may have to replace the expansion valve, thats a little higher that I would like to see on the high side.

Anyway, just thought I would put those numbers out there for inquiring minds.

The low side is much lower than what you see on a car, but the 20 to 30 number is what Evans Tempcon shows in their technical literature.

[encantotom]

i had my AC serviced today for the dash. it was 100 degrees outside when i did it. low side was about 30 and high side was about 250.

they evacuated the system, pressurized with nitrogen, checked for leaks and found none and re evacuated and then put freon in.

dash blew about 58-59 degree air.

tom

[fulltiming]

Tom, those numbers are very close to what I got today after adding 2-12 oz cans of 134a. I had 32 on the low side and 220 on the high side but the outside temperature was about 5 degrees lower than yours and that will lower the pressures a little. My dash vents were blowing about 60 degrees. Before adding the 134a my dash air was blowing 80 degree air.

Richard, your ambient temperature should have been close to mine so you do have an issue with that 325 psi high pressure reading.

[Richard and Rhonda]

As much as I hate to tear into a system that didn't leak, and was blowing cold air, I think the expansion valve needs replacing. I am afraid it will shorten the life of the compressor if I don't fix this.

Thanks for posting your numbers, it confirmed my suspicions.

[Richard and Rhonda]

Ok, pulled the old TXV out and found a replacement at a local AC parts house. Installed the new one, pulled vacuum for 30 minutes and then let of sit to check for leaks. No leaks so I refilled with R134a. After adjusting gas charge, I had 25 psi on the low side, 275 on the high side, and 62 degree air at the vent

[fulltiming]

Great Richard. Those numbers are much closer to what Tom and I experienced. The high side pressure decrease from 325 to 275 should have a positive impact on the longevity of the compressor. I am assuming that the ambient temperature was around 95 based on the dash air temperature of 62.

[express1]

Do you guys have a different rate for fixing things that are not broken?
Or do you not have a rate?

[Richard and Rhonda]

Point well taken Matt. However I was seeing discharge pressures as high as 375, and one of my first projects with the coach was replacing a siezed compressor. In hindsight, I think the high pressures contributed to the compressor failure. Better a 30 valve replacement than a 450 compressor.

Now to answer your real question. My bride likes it cold, real cold. I just don't think you can compensate me the same way she does :-)

[express1]

the boss may not always be right. but the boss is BOSS!
But I do have a set of gauges and would like to check my pressures at some point maybe in Creede. I am in need of lessons on how to use them.

[encantotom]

the rates are very dependent on alot of factors. as i tell anyone who tries to pay me for helping them, you can't afford me.....

the same way with most of us. it certainly is a therapy kind of thing for me. i just spent the evening out in the coach building a resistor network and tuning it for the dual temp sensors i put on a digital gauge.

i was running the coach at fast idle and the genny and the neighbors didnt even call the police!

look forward to seeing you in colorado.

tom

[2dogs]

Oh, how does one get at the expansion valve? ours i think--- is behind the the bumper passenger side. in the bay with the generator fan. but i see no way to get at it... any suggestions? or pictures? much appreciated.. Brian

[fulltiming]

If yours is in the same location as the early 1990's models, you are correct. The process on the early 90's models is:

Open passenger's side front compartment where the generator fan is located. Remove the 3 screws that hold the metal plate at the front corner of the bay and remove the metal plate. Slide out the wooden divider that has insulation glued to it. Remove the 3 screws that hold the metal base that the wooden divider was resting on to the compartment floor. Remove the screws from the lowest of the three panels at the front of the compartment and remove the vented plate. The expansion valve should now be accessible behind the vented plate. The two larger plates above cover the coils and the blower motors.

[Richard and Rhonda]

The guages and voltmeter are in the coach. I'll be happy to do AC 101 in Creede.

And I am exactly like Tom, if you try to pay me you can't afford me. It's therapy.

The rate is cheaper if you are trying to do it yourself and need some support. It's exorbitant if you don't know how to do it, but you feel the need tell me how.

[folivier]

I'd like to have an AC 101 in Creede!

[chockwald]

Just returned from my mechanic where he topped off my refrigerant for my dash A/C. It was only putting out about 60 degrees in the vents. After he added 1 lb. the vent temp dropped to 48 degrees. The low pressure was around 20 and the high around 175-180. I am still using the manual shut off that Tom and Michael installed for the dryer which will not cycle on and off as it should, and that has helped keep the system from freezing up.

[express1]

Is that for some sort of earth quake machine?