I just added the 20 oz. of r134 as per factory spec. System was vacuumed and had no leaks. This is on a 2001 jeep cherokee. My gauges read 37 on the low side and 300 on the high. The air is blowing cool but should be much colder. What's going on here? Am I overcharged or is there air in the system? Any help would be appreciated. Thanks!
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AC help please
- Thread starter brielly
- Start date
Agreen
NAXJA Forum User
- Location
- Charleston
A low low side pressure and high high side pressure indicate that you have a blockage somewhere. Did any other work get done before vacuuming and recharging?
lawsoncl
NAXJA Forum User
- Location
- North Idaho
The answer depends a bit on the ambient temperature. They don't seem that far off if it was in the 90s outside.
I'm with AGreen on this one, you likely have a blockage somewhere in the system.
At 80 degree ambient you should be seeing 40-50 on the low side and 175-210 on the high side.
I had a similar issue after changing out a leaking condenser coil (the one in front of the rad). The issue was that my new one had a blockage causing similar pressures to what you posted. Once I changed it the second time, the pressures (and temps) were perfect.
FWIW, here are the pressure charts I use:
https://acprocold.com/faq/r-134a-system-pressure-chart/
HTH
Todd
At 80 degree ambient you should be seeing 40-50 on the low side and 175-210 on the high side.
I had a similar issue after changing out a leaking condenser coil (the one in front of the rad). The issue was that my new one had a blockage causing similar pressures to what you posted. Once I changed it the second time, the pressures (and temps) were perfect.
FWIW, here are the pressure charts I use:
https://acprocold.com/faq/r-134a-system-pressure-chart/
HTH
Todd
Agreen
NAXJA Forum User
- Location
- Charleston
The better question is "why isn't your electric fan coming on when the AC compressor is running"?
(The electric fan needs to be on when the AC compressor is running, BTW)
(The electric fan needs to be on when the AC compressor is running, BTW)
Agreen
NAXJA Forum User
- Location
- Charleston
Interesting. I just went and read the manual and found that the fan will come on with a high refrigerant pressure and off when it falls back to 235 psi. I swear. Some of these manufacturers just have to be different just because.
From the thing:
The dual function switch controls the electric cool-
ing fan operation by monitoring refrigerant line pres-
sures. When the discharge line pressure rises above
1900 to 2200 kPa (280 to 320 psi) the fan will turn
on. The cooling fan will turn off when the discharge
line pressure drops to 1600 kPa (235 psi).
Still. The high pressure is too high, and the low pressure is too low. My original question still stands.
From the thing:
The dual function switch controls the electric cool-
ing fan operation by monitoring refrigerant line pres-
sures. When the discharge line pressure rises above
1900 to 2200 kPa (280 to 320 psi) the fan will turn
on. The cooling fan will turn off when the discharge
line pressure drops to 1600 kPa (235 psi).
Still. The high pressure is too high, and the low pressure is too low. My original question still stands.
Agreen
NAXJA Forum User
- Location
- Charleston
Well there's already a fan running (clutch driven fan) so I guess the electric is a backup for high pressure. I re-read it and made absolutely sure that it only comes on with a high refrigerant pressure or a high engine coolant temp. The refrigerant pressure shouldn't get that high under normal idle circumstances. Most other manufacturers would run the condenser fan all the time, but then again the radiators and condensers on most other cars aren't 6 feet wide and 4 inches tall.
I hate to say it, but you'll need to bust open some lines and flush everything. I like using brake cleaner and compressed air. Don't flush the orifice tube, compressor, or the receiver. I use like half a can in the condenser and the other half in the evaporator, then blow it out into a clean rag. I also look for sludge in the rag after blowing it out. If black crud comes out, you might need to replace the compressor.
tjmotter sounds like he's been down this path before. I never put AC parts on that haven't been thoroughly flushed for that exact reason.
I hate to say it, but you'll need to bust open some lines and flush everything. I like using brake cleaner and compressed air. Don't flush the orifice tube, compressor, or the receiver. I use like half a can in the condenser and the other half in the evaporator, then blow it out into a clean rag. I also look for sludge in the rag after blowing it out. If black crud comes out, you might need to replace the compressor.
tjmotter sounds like he's been down this path before. I never put AC parts on that haven't been thoroughly flushed for that exact reason.
Please explain your statement; " System was vacuumed and had no leaks."
Specifically;
1. How long was your system vacuumed?
2. What was the lowest micron reading you obtained for your system?
3. How long did you continue holding the lowest micron vacuum reading?
4. What was your criteria to say you "had no leaks"?
Best regards,
CJR
Specifically;
1. How long was your system vacuumed?
2. What was the lowest micron reading you obtained for your system?
3. How long did you continue holding the lowest micron vacuum reading?
4. What was your criteria to say you "had no leaks"?
Best regards,
CJR
RCP Phx
NAXJA Forum User
- Location
- Phoenix,Az
Vacumm and pressure testing are different but that really doesn't change any comments so far. Yesterday my friend came over with his SS and a leak he couldn't find, he had applied dye and swears he looked everywhere and didn't see anything. We put it on the lift so we could make sure and see every inch of line and hose connections. After about to say "no leaks", we where able to see up under the clutch hub and sure as "sh*t" it stood out as "bright as day"!
Based on what you have stated;
1. No AC system leaks.
2. High refrigerant discharge pressure.
3. Vacuum pressure.
In my view, your system has;
1. Excessive ice crystal blockage at the orifice.
2. The blocked orifice is acting like a closed "throttling valve" and increasing the refrigerant discharge pressure.
3. The blocked orifice is also limiting the amount of liquid refrigerant that can "flash to gas" (i.e. phase change of liquid refrigerant to gas refrigerant) in the evaporator.
4. Because less liquid refrigerant is being "flashed to gas", in the evaporator coil, less heat is being extracted from the warm air that is flowing through the evaporator.
5. To remove the ice, the ice must first melt, then vaporize to water vapor and then the water vapor must be extracted by the vacuum. The lower the vacuum, the faster the water vapor can be extracted from the AC system.
6. It takes time to extract ALL the water vapor from the AC system. Sometimes, the water vapor, extracted from the liquid refrigerant, gets trapped in pockets in the AC system and can't be completely vacuum extracted out.
In my view, you need to pull a vacuum of 5000 microns or LESS for a couple of hours or more. Likewise, to remove any trapped pockets of water vapor it is helpful to vacuum the system, run/recharge the AC to redistribute the refrigerant/water vapor, then vacuum again to remove more water vapor, and then recharge with refrigerant. Sometimes I'll repeat this "vacuum/recharging AC" cycling a number of times to thoroughly remove ALL the water vapor. Then if this approach dosn't work, its time to pull the AC system apart.
Best regards,
CJR
1. No AC system leaks.
2. High refrigerant discharge pressure.
3. Vacuum pressure.
In my view, your system has;
1. Excessive ice crystal blockage at the orifice.
2. The blocked orifice is acting like a closed "throttling valve" and increasing the refrigerant discharge pressure.
3. The blocked orifice is also limiting the amount of liquid refrigerant that can "flash to gas" (i.e. phase change of liquid refrigerant to gas refrigerant) in the evaporator.
4. Because less liquid refrigerant is being "flashed to gas", in the evaporator coil, less heat is being extracted from the warm air that is flowing through the evaporator.
5. To remove the ice, the ice must first melt, then vaporize to water vapor and then the water vapor must be extracted by the vacuum. The lower the vacuum, the faster the water vapor can be extracted from the AC system.
6. It takes time to extract ALL the water vapor from the AC system. Sometimes, the water vapor, extracted from the liquid refrigerant, gets trapped in pockets in the AC system and can't be completely vacuum extracted out.
In my view, you need to pull a vacuum of 5000 microns or LESS for a couple of hours or more. Likewise, to remove any trapped pockets of water vapor it is helpful to vacuum the system, run/recharge the AC to redistribute the refrigerant/water vapor, then vacuum again to remove more water vapor, and then recharge with refrigerant. Sometimes I'll repeat this "vacuum/recharging AC" cycling a number of times to thoroughly remove ALL the water vapor. Then if this approach dosn't work, its time to pull the AC system apart.
Best regards,
CJR
