00_buck

My blower motor seems to reduce in speed when I put it on Max A/C. Basically my (from 1-4, 4 being highest) number 4 setting on normal A/C is my number 3 setting on max for fan speed. Anybody have a clue why this is? Do I need a new motor? I'm going to check the pressure on my system tomorrow too. It gets cold if I'm driving and it's on normal or max but if I sit still it gets to be just moderately cool and it's barely 80* outside (but this shouldn't affect the blower motor).

2000BlkGtConvgobucks

Ok, anybody out there please correct me if im wrong here. With our cars like most cars, the "normal" setting on your ac brings in fresh outside air and cools it, the "max" setting recirculates the air within the cab to create an even colder environment. Knowing this, i would make a few guesses. Your cars ventilation system may not be completely engaging into the "max" position, the closed system might either have a blockage or possibly even a leak. It could also be that the ac is fully engaging into the closed "max" system which causes a slightly more restricted mass of air flow pushing out of the vents(i feel like my car does this and that it is how it was designed). As long as you are receiving a consistent airflow from your vents then there shouldn't be a problem with your blower so you can rule that one out. Your second problem is a textbook symptom of an undercharged system. Go to napa, get a pressure gauge and recharge your system. Im willing to bet that it fixes both your problems. It doesn't matter if your air doesn't blow very hard if its ICE cold! Good luck, hope this helps

00_buck

thanks for that bit. I had the gauge hooked up to it and ran it on max ac. I'd say it would run on this cycle every 24 seconds: goes up to alert (45 psi), comes down to "filled" (35 psi), down to borderline low (25 psi), then back up to alert (45 psi). Does this in 24 second intervals. Is this normal? A/C seemed cold but it was only 64 degrees outside. I'm wondering if it may be overfilled or something.

2000BlkGtConvgobucks

As i said before, do not quote me on anything that i advise in this post because i know the least about the hvac system than any other component of our cars. I am only giving advice because nobody else here is chiming in, i don't want to just leave you hanging. Given my disclaimer, i think one of two things. Your cars ac system is still under charged, or you are having a problem that i am unaware of(possibly an issue with the compressor or a pressure sensor? From my experience, when your ac goes into the cycle that you have described, it is in a sense "almost" working correctly. The only problem is that the under-charged system eventually hits a low pressure after a few seconds which triggers the low pressure sensor causing the compressor to shut down, which in turn causes the never ending cycle you are experiencing. The compressor kicks on, runs for a few seconds, hits low pressure, then shuts off. Then it does it all over again, and again, etc. Basically, what im saying is that your AC system should never drop below the 35-40 psi level after the compressor engages(the pressure may jump much higher than 45psi when the compressor is NOT engaged,meaning the AC compressor is turned off. Don't worry about this unless it is in extreme ranges above 100psi, always wear eye protection when working on this stuff!). Since your system is hitting a low of 25psi there is definitely an issue with your systems pressure. You probably have a leaking o-ring or seal, i think that is 95% of all low pressure issues. I hope this helped, good luck, keep us posted.
Mark