Ok group, I need some help-
I have a 2002 Honda Odyssey with 185,000 miles that is experiencing an A/C problem. I’ll try to share what I can about the background and troubleshooting that has been done thus far:
In early May we noticed the A/C wasn’t performing well. Next thing we knew the compressor wouldn’t kick on at all (this condition may have happened all at once, not really sure at this point)
Action: I researched and suspected that the Freon was low so I bought a can with gauge and attempted to fill. Well, I did not yet know the compressor had to be jumped to allow the system to take a charge, so I tried to squeeze some in anyhow. The static pressure was around 90 psi, when I started. This pressure did not change much with the trigger squeezed, so I gave up and drove home. When I started driving the Compressor kicked in and I got cold air on the 7 min drive home. When I was home I popped the hood and started putting in the Freon with the A/C on high. The pressure was reading around 25-30 psi with the compressor engaged. After a minute the compressor kicked off and wouldn’t reengage unless I drove around the block and quickly adding more until the compressor kicked off a minute later. After three or four trips I had emptied the bottle and the pressure was reading around 30-35 psi on an 80-degree day.
Result: I though this may have fixed the issue but was puzzled why the compressor would kick off when the vehicle was not moving. It seemed to work while the van was moving for a few weeks. Around this time I noticed that the van’s temp was climbing above its normal range while the A/C was not working. I was planning to take the van into the dealership for an airbag recall the next day so I had the dealer check out the overheating issue but I did not have them look into the A/C. They suspected the water pump was leaking antifreeze because the fluid was leaking at the bottom of the timing belt cover and it was low on fluid. Obviously the water pump needed to be addressed and they quoted the job along with timing belt and the whole 105k-mile tune-up service.
Action: I tackled the water pump and timing belt job successfully over that weekend and replace the side and front mounts that were in much need of replacement. When I got it all back together the A/C compressor still did not engage. I then began further troubleshooting on the A/C and this is where I need your help.
I did a little more research and tested the compressor and clutch by jumping the relay after checking all related fuses. It did not work at first because I had stretched the male/female connection on the wiring closest to the compressor when I raised the engine to lift it over the front engine mount. After resetting the connection the compressor engaged fine and the system cooled well. Next I jumped the 1 and 4 prong on the trinary pressure switch and the fans kicked on and the RPMs increased in anticipation of the compressor kicking in but it did not kick on. Suspecting that the system was low on Freon again I bought another can with sealant additives and added a little. Nothing changed so with a little frustration I kept the compressor jumped and added the whole can, about 30 seconds later the relief valve let off some pressure (that was fun).
At this point I took it to a local technician who has 20 years experience and works often with A/C systems. He found the system to be 90 percent full and also confirmed my testing of the relay and switch. He brought the system up to full, but I do not believe that he did a system withdraw and refill. He tried replacing the blower resister, seeing that it was a common problem with these but that did not make any difference. His final thought after a half hour of testing was that it is likely the HVAC control head and quoted replacing this. I didn’t have a lot of confidence that this is my next best move so I took it to another shop and after 3 hours of trouble shooting they wanted to try and replace the blower resister which the first tech actually did in half the time, discovering that it wasn’t the problem.
I have done a little more reading and suspect that I may have a bad expansion valve or receiver/drier possibly causing the compressor to get a signal not to engage. Is this possible? Also, I suspect the Engine Coolant Temperature Sensor to be bad, especially because it was getting hot when the system was low on coolant. But it is still working and reading what appear to be a normal temperature reading and the engine is starting and running like normal. Could the ECT Sensor be the cause even when it seems to be reading correctly everywhere else? I noticed the CKP Sensor got soaked at the bottom of the timing belt cover when the pump went out. Could this sensor cause an impact on the compressor? It is reading RPMs correctly on the gage. Maybe the first tech was right…
Beyond all this I have a multimeter and circuit tester to dig a little deeper with but not sure I have the skill to test the whole system. Perhaps this post and tackling the water pump/timing belt shows that I have some commitment to seeing it through though. Can you guys help? Thanks!