AC in my 2003 Suburban has been less than stellar lately (a must have here in sunny Arizona in August!). Cooling has been marginal, at best, when using just the front system only. In order to get acceptably cool air I needed to turn the back system on as well.
Suspecting low refrigerant levels I connected up the old ELM327 and fired up Torque Pro, graphing AC Relay Status (0x221100, bit 2) and AC Hi Side Pressure (0x221144). Sure enough, Hi side pressure was dropping below the cutoff threshold and so the AC Relay was cycling on & off. Running the rear system in addition to the front increased the heat transfer load and increased the pressure just enough to keep the AC relay On.
I removed the cap on the low-side/charging port, gave it a blast of air to remove any particles, and added refrigerant, keeping track of low- & hi-side and pressures. The system stabilized and all appeared to be in order.
Congratulating myself (prematurely as it turns out), I disconnected the fitting from the low side port only to hear it start leaking, slowly, undeniably. Hoping I might be able to re-seat the valve I gently depressed the stem but no luck. The seal on the Schrader valve was not holding.
Rather than attempt to do an in-situ replacement of the valve stem I decided to let discretion get the better part of valor. Fortunately, the local Automotive AC shop was able to fit me in right-away and an hour later the AC was running better than it had been for quite some time. I ended up getting a standard service plus replacement of both the low- & hi-side port stems.
Here is a closeup of the bottom tip of the Schrader valve stem (note: tip width at the end of the valve is 1.5mm). Notice the deformation of the lower seal.
It is always the little things that nail you. In retrospect, it should not be surprising given that this part was likely original to the vehicle.
Suspecting low refrigerant levels I connected up the old ELM327 and fired up Torque Pro, graphing AC Relay Status (0x221100, bit 2) and AC Hi Side Pressure (0x221144). Sure enough, Hi side pressure was dropping below the cutoff threshold and so the AC Relay was cycling on & off. Running the rear system in addition to the front increased the heat transfer load and increased the pressure just enough to keep the AC relay On.
I removed the cap on the low-side/charging port, gave it a blast of air to remove any particles, and added refrigerant, keeping track of low- & hi-side and pressures. The system stabilized and all appeared to be in order.
Congratulating myself (prematurely as it turns out), I disconnected the fitting from the low side port only to hear it start leaking, slowly, undeniably. Hoping I might be able to re-seat the valve I gently depressed the stem but no luck. The seal on the Schrader valve was not holding.
Rather than attempt to do an in-situ replacement of the valve stem I decided to let discretion get the better part of valor. Fortunately, the local Automotive AC shop was able to fit me in right-away and an hour later the AC was running better than it had been for quite some time. I ended up getting a standard service plus replacement of both the low- & hi-side port stems.
Here is a closeup of the bottom tip of the Schrader valve stem (note: tip width at the end of the valve is 1.5mm). Notice the deformation of the lower seal.
It is always the little things that nail you. In retrospect, it should not be surprising given that this part was likely original to the vehicle.
