Automotive Air Conditioning Information Forum

Greetings,

I have a vehicle exhibiting odd R134a refrigerant pressure behavior and the compressor shuts down every 15-30 seconds. With an ambient temperature of about 75°F and the engine at operating temperature, the high side pressure settles at about 225 psi while the low side is at 28 psi. Within a 30-second timeframe, the high side drops to 215 psi and the low side to about 20 psi, causing the compressor to shut down. The condenser fans operate when the compressor is on, but the temperature at the vent does not drop below 50°F.

So far, the system has been vacuumed and refilled to spec by weight, the high pressure sensor seems to check out and just in case, the relay was swapped.

Does this seem like failure of a component or a sensor issue?

Thanks for the help!

Year, make, model, engine?

2016 Acura MDX 3.5 V6
Thanks

What was the rpm at which you got those readings? Plz provide readings at 1800 rpm.
Why was work done to the system?
225 psi at 75F is a bit high and doesn't leave much leeway when the ambient gets to 95

The rpms were at 1500. The work was done due the present issue. Schrader valves were replaced due to sniffer finding trace gas.

Unbeknownst to many, schraders seldom accomplish total sealing. The final seal is actually the plastic cap that goes over the shader.
I have worked on cars that had no sealing caps at all…..and they all leaked using a sniffer.
I have a kit of assorted caps to correct this problem. For some unknown reason there has been no standardization of these caps.
Of course u must use a shrader tool and be sure they are snug as the first check. I have come across many loose shraders. Snug, not tight….go gently

I am suspicious of the expansion device not opening sufficiently .
Has the system ever had a compressor grenade

I figured out the root cause of my issue. When the temperature of the evaporator core is nearing freezing, the compressor cycles on and off. I pulled the sensor from the evap core, the compressor no longer turns off and the air is coming out very cold (too cold). I still have to verify the sensor is operating in the correct range but its a step in the right direction.

Thanks for the help!

firestarter001 wrote: ↑Sun Jun 02, 2024 9:28 am I figured out the root cause of my issue. When the temperature of the evaporator core is nearing freezing, the compressor cycles on and off. I pulled the sensor from the evap core, the compressor no longer turns off and the air is coming out very cold (too cold). I still have to verify the sensor is operating in the correct range but its a step in the right direction.

Good detective work.