Compressor Cycles every 30 seconds

[ACDadforever12]

I am having trouble determining what is wrong with AC on my 2014 Nissan Pathfinder. These are notes detailing the problems and findings:
1. Vents blow warm when vehicle is not moving, and gets cooler when after about one minute movement.
2. AC compressor and fans cycle approximately every 30 seconds.
3. The attachment shows low and high side pressures over three minutes. The beginning of the low side spike is when the compressor turns off. The peak of the spike is when the compressor turns on.
4. Ambient was approximately 80F during testing.
5. Compressor discharge is hot.
6. Condenser outlet is ambient temperature.
7. Compressor suction is slightly cool, but not cold. No condensation on suction line.
8. AC has never been serviced since new.

Pathfinder AC pressures.jpg (110.03 KiB) Viewed 4962 times

Thanks for any help you can provide.

[tbirdtbird]

Most likely low on R134.
Please do not try to add any with those ACPro cans from the parts store, which also have sealant. Charge MUST be weighed in. Never use sealer.
All systems will lose a small amount of R134 over the years from attrition.
System needs to be evacuated by a recovery machine which will tell how much 134 is in there, then vacuumed down, and correct weight of charge installed. This is your very first step.
Then obtain a sniffer and sniff all joints and connections and shaft seal and evap drain under the car to see if you have a leak. For shaft seal, put shower cap over com with belt off, and leave overnight. Then sniff inside bag the next day.
Report back

[DetroitAC]

You are just low on refrigerant, completely normal for the age of your Pathfinder. Refrigerant permeates out of hoses and fittings, I doubt you have a leak based on what you wrote, just get it recharged to the proper refrigerant level.

[ACDadforever12]

I tried to vacuum the system and refill with the appropriate amount of refrigerant. This did not help the issue. Is there anything else that could be causing the issue? I think there might be a blockage in the receiver/drier or condenser. I really hope there is not a blockage in the TXVs because they are likely hard to get to.

[JohnHere]

How did you go about evacuating and recharging it? What pressures are you seeing?

[tbirdtbird]

Agree with John totally. How long did you vacuum? What was the reading of the vacuum, ie 29.9 or something else? Running pressures? Center vent temp?
Please remember that the more details you can feed us the better we can help you. We are not standing there by your car to observe things. We are behind a computer screen

[JohnHere]

When a TXV gets blocked, it's usually caused by the desiccant bag in the R/D breaking open. Then the beads travel down the liquid line and lodge in the TXV. If that happens, you would see very low pressures on your low-side gauge. Sometimes, the low side will even go into a vacuum. As already said, the system is probably just low on refrigerant.

[ACDadforever12]

I am doing the work myself and have access to a manifold and vacuum pump.

I am quite certain the system is not low on refrigerant.

These are the last steps I took after talking to the people on the forum:
1. Vacuumed the system to around 29 in Hg for 30 minutes.
2. Charged the system with r134a cans to the weight listed on the Nissan Label. The cans do not have sealer.
3. Pressures were 30 psi low and 275 psi high.
4. Ambient temperature was 91 degrees.
5. Temperature from center vent was 92 degrees.

[Tim]

I am doing the work myself and have access to a manifold and vacuum pump.

I am quite certain the system is not low on refrigerant.

These are the last steps I took after talking to the people on the forum:
1. Vacuumed the system to around 29 in Hg for 30 minutes.
2. Charged the system with r134a cans to the weight listed on the Nissan Label. The cans do not have sealer.
3. Pressures were 30 psi low and 275 psi high.
4. Ambient temperature was 91 degrees.
5. Temperature from center vent was 92 degrees.

Check you're not getting hot water in the heater core. Either by making sure the diverter doors are working or crimping hot water lines for a short time.

[tbirdtbird]

Let's touch on a few points of interest.
1. The longer you vacuum, the better the system will work. Not sure what 'about 29' means. Should also vac for at least an hr, it takes that long to boil off any moisture in the system. You are not just removing air.
2. Using a ray gun type IR temp gun, or any other method of temp reading you have, record the temp in and out of the condenser as close to the cond. as possible.
3. grab the pipe into and out of the evap if at all possible and compare. The two temps should be about the same.
4. Tim has brought up an important point, being so-called reheating, whereby the hot air from the heater core is being mixed in with the cold air. The hot air will win every time.
5. Your hi side is kind of high. Using a water hose, and not a plant mister, mist water onto the condenser and see what that does to the hi side pressure.

Report back all findings