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AC Manifold Gauge Set

What should the connected subject gauges (Blue LP and Red HP) read for a fully charged system in my coach 2001 U320?  Cannot find anything in the FT documentation box.

The measured temperature at the dash outlets is 62 degrees and I believe it should read around 42-45?
Fiddler
1959 Parris Island grad
40' 2001 U320 Build 5875
1999 Suburban K1500 toad
1986 Corvette Pacecar
ssoftail@comcast.net

Re: AC Manifold Gauge Set

Reply #1 –
When I replaced my compressor and expansion valve I was getting around 20 on the low side (blue) and 150 on the high side (red) the ambient temperature was around 80 deg. The thermostat cuts my compressor off when the register gets to 40 deg. These numbers are way off from searches I did on ref. 134a maybe because we have the condenser fan running all the time or some other characteristic of the coach causes the difference. I first used the 65 psi. low and 250 high when I charged it and it never go cold. I then lowered the pressure until I had 40 deg. at the register and made a note of the pressures for future use on my coach.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: AC Manifold Gauge Set

Reply #2 –
The pressures and temperatures are subject to a correction for ambient temperature.  I will try to find a link to a chart my chart is at work.
Toby a 94 u280
Cummins 8.3
6 speed Allison
Exhaust brake


Adopted by Derek and Annabelle

Re: AC Manifold Gauge Set

Reply #3 –
Quote from: its toby –
The pressures and temperatures are subject to a correction for ambient temperature.  I will try to find a link to a chart my chart is at work.
[/quote

That was the chart I was referring to when I said the pressures didn't make cold air on my coach
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: AC Manifold Gauge Set

Reply #4 –
Pressures will go up and down based on temperature of the condenser and evaporator--which change based on ambient temp, airflow, cleanliness, etc.

You are technically charging to subcool method with a TXV. Fixed orifice, use superheat (or grab the return line and make sure it's cool).

If you are trying to achieve a certain pressure, you are chasing your tail. The good news is that this system is large and because it is a TXV is forgiving to not achieving exact charge amount. I think mine took around 2 or 3 lbs to get what I was looking for, but I can't remember exactly.

The concept is to achieve enough refrigerant in the system to ensure the TXV is getting subcooled liquid. Too much charge, and the liquid backs up into the condenser and possibly to the compressor.
1998 U270 34'

Re: AC Manifold Gauge Set

Reply #5 –
It seems that with that pressure split there may be something amiss. Are you getting good heat transfer at the condenser and evaporator? Is the hit cold blend door going to full cold? Was there an inline filter in the system?
Toby a 94 u280
Cummins 8.3
6 speed Allison
Exhaust brake


Adopted by Derek and Annabelle

Re: AC Manifold Gauge Set

Reply #6 –
Quote from: craneman –
When I replaced my compressor and expansion valve I was getting around 20 on the low side (blue) and 150 on the high side (red) the ambient temperature was around 80 deg. The thermostat cuts my compressor off when the register gets to 40 deg. These numbers are way off from searches I did on ref. 134a maybe because we have the condenser fan running all the time or some other characteristic of the coach causes the difference. I first used the 65 psi. low and 250 high when I charged it and it never go cold. I then lowered the pressure until I had 40 deg. at the register and made a note of the pressures for future use on my coach.
Quote from: craneman –
When I replaced my compressor and expansion valve I was getting around 20 on the low side (blue) and 150 on the high side (red) the ambient temperature was around 80 deg. The thermostat cuts my compressor off when the register gets to 40 deg. These numbers are way off from searches I did on ref. 134a maybe because we have the condenser fan running all the time or some other characteristic of the coach causes the difference. I first used the 65 psi. low and 250 high when I charged it and it never go cold. I then lowered the pressure until I had 40 deg. at the register and made a note of the pressures for future use on my coach.
Looking for a list of parts.
Need Receiver dryer part# also compressor part# .found receiver/dryer loaded up. flushed lines already. Parts sources? Thanks
99 40' U270 #5574
2010 Honda Element
Hot Springs Village, AR.
K5IIK
 

Re: AC Manifold Gauge Set

Reply #7 –
Compressor number Seltec 488-46018 expansion valve, MEI 1600, drier RD 7127
These numbers fit my 1999 U320 I think I found the numbers on Barry's website or on the forum search
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean