Pathfinder AC diagnosis

[RatLabGuy]

2008 Pathfinder. Last summer the AC faded to "not cool", by the first time neededt his year, functionally nonexistant (just blows hot air).
Tested w/ manifold gauges today, low side was ~5 lbs, same on high, bc compressor wasn't kicking on - presumably low pressue switch preventing it.

I know the right thing to do is to evacuate the system and start totally fresh, but before commiting to that I wanted to esnure it would hold something. Since it had "some" pressure, thus likely not a big leak somewhere.... just age (?), went ahead and added rest of a partial can of 134A I had.
That managed to get it up to ~20 lbs, compressor started working. high side up to ~90 lbs. OK that's promising. Started a 2nd can. It got up to ~35ish lbs, and stalled taking more, w/ high side then ~150?.

What suprised me though is that the vent temp never changed. I wouldn't expect it to be COLD, but at least starting to show something, Is this wrong? Also it was sitting several minutes w/o showing much change, like had asymptoded by then.

I guess the question is, what could cause it to still blow hot, but be within a reasonable pressure range? Is it that there could be moisture in the lines that prevents the 134a from getting as compressed and making cold?

EDIT - I just realized it was very hot today, >90 in the garage. This probably is affecting the effective range....?

 

[Wes]

I believe with ambient temp being that high your pressure on the low side should be like 45-55 if I remember the chart correctly, but if it quit taking it I’m not sure.

 

[jeepyjman]

150 isnt high enough with that ambient temp. Need more freon to get cold temps.

 

[shawn]

Look at the pressure chart for 134a. Probably still need two more cans.

 

[Blkvoodoo]

should be a tag on core support or hood stating type of refrigerant, oil and quantity, yellow usually

 

[RatLabGuy]

Yep. This morning it wasn't so hot. Hooked up gauges. Only 12 on low side, 90 on high. Dang it.
But then I realized w ambient temp lower (78) that would happen... Right? Otherwise it lost some since yesterday.

Added the rest of the can, or as much as I could get out. Brought it up to 30/190. Vent temp in low 70s, feels a bit cooler than ambient, so yeah, it's heading there. Unfortunately Jonas had to take the car, so I'll nab another can, probably one w dye for good measure, and see what happens tonight when it's cool again.

Question - with the car off, or the compressor off, the low side pressure is really high, like 70. What's that all about? Is it bc when dormant there's a little leakage around the compressor rings so the high/low mixes?

 

[RatLabGuy]

should be a tag on core support or hood stating type of refrigerant, oil and quantity, yellow usually

Good call. Too bad the car just drove away, and I never thought to look down and see if there's something there LOL

 

[Blkvoodoo]

Good call. Too bad the car just drove away, and I never thought to look down and see if there's something there LOL

Walmart would probably be your cheapest place for r134a, last I saw $7-8 a 14oz can, parts stores are double or more for same thing

 

[shawn]

Walmart would probably be your cheapest place for r134a, last I saw $7-8 a 14oz can, parts stores are double or more for same thing

Walmart is cheapest for motor oil, filters, and freon. Sometimes you have to dig around.

so hot. Hooked up gauges. Only 12 on low side, 90 on high. Dang it.
But then I realized w ambient temp lower (78) that would happen... Right?

 

[shawn]

quit taking it I’m not sure.

It freezes up. Have to shake the cans, turn them upside down, work the valves on the gauges, etc

Is it bc when dormant there's a little leakage around the compressor rings so the high/low mixes?

Without the compressor running, the pressure in the system normalizes. It'll leak through the expansion valve. That's the whistling sound you hear when you shut off the engine.

 

[Wes]

It freezes up. Have to shake the cans, turn them upside down, work the valves on the gauges, etc


Without the compressor running, the pressure in the system normalizes. It'll leak through the expansion valve. That's the whistling sound you hear when you shut off the engine.

You’re right. I remember the can freezing and having to turn it upside down now. It’s been a while.

 

[Scooter402]

Does the Pathfinder have a functioning condenser fan? I had an '06 Ram 2500 that got to where the AC would blow just sort of tepid, but would cool some when moving. Recharged it, sort of helped a little. Would be nice and cool riding down the road though. Got to poking around and found that the condenser fan had quit. Replacing it solved that problem.

 

[Jody Treadway]

It freezes up. Have to shake the cans, turn them upside down, work the valves on the gauges, etc


Without the compressor running, the pressure in the system normalizes. It'll leak through the expansion valve. That's the whistling sound you hear when you shut off the engine.

WRONG.
tHAT'S THE TURBO.