I have 2014 Jeep Grand Cherokee with AC blowing only slightly cool at low fan speed. Previous I’ve done over the past few years, replaced blend door gears and blend door control module both sides. Charged the Freon with charge canister from Autozone 3 years ago and AC worked good.
1 year ago the AC started to underperform again and thought I’d charge it again, but when I hooked it up to the low side it showed the pressure was in the normal range. It’s been only mildly cool since then, works better at low fan speed. Also I know the blend door on passenger side has failed again so I keep the vent closed. In addition the driver side blend door is now making noises again. Saw a post on YT someone completely broke down the AC box and showed how the gasket that Jeep used that the blend door closes against to make a seal when closed as it’s not plastic on plastic degrades overtime and the sticky adhesive starts to catch the blend door, and overtime either the plastic gear or driver module will keep failing as they try to overcome the extra torque needed. This guy had replaced several gears amd drivers and wanted to know why. Anyway even if I solve the why the AC isn’t cold problem, I’m still going to have to solve the blend door problem.
If anyone on here can comment/advise on the not blowing cold issue on the driver side with a known good blend door (at the moment) for example should I not trust the home charge kit and take it into a shop to have it charged and check for leaks? And secondly, any recommendations on the blend door gears and driver modules, eg are there DIY kits to fix all this from under the dash without pulling the box?
Most of us here feel that you shouldn’t do A/C work without proper shop equipment and proper training.
I’ve been an automotive engineer for 25 years, designing every electronic control module used. I’m also have extensive experience in electro-mechanical, electro-pneumatic, and electro-hydraulic systems. But everyone no matter their experience level requires help and guidance from people who are experts within certain subsystems within the vehicle, eg HVAC system. Also I only taken my car in for work twice in the last 25 years, everything else I’ve fixed myself. I’m not saying any of this to brag but I feel the need to establish that you are not talking to a newbie here, I’ve been in the industry my whole life, just looking for advice about this particular problem from this community.
Also as an aside I have an appointment with an AC specialist shop in my area on Wednesday, they are going to diagnose and recharge and look for leaks if needed. Even still I would like to hear from multiple people and experts because what I’ve found over the years is you always learn something new from someone who has insight or knowledge that can be very helpful. Thank you
Just remember that using a home charge kit from AZ, you are only seeing one side of the pressures, you need to use a manifold gauge set that of course shows both the low side as well as the head pressure (high side)… And the only true way to know how much freon you have in the system is to remove it and weigh it, and then fill it to spec after pulling a vacuum on it to get any moisture in the system out…
So not knocking your mechanical ability in any way form or fashion, but AC needs to be handled by someone with the proper tools to do so, rather that is YOU or your mechanic… Otherwise you are no different then any other 2 can Sam out there (spray and pray), doesn’t matter if you can build the space shuttle from scratch in your basement… lol
Low on freon, leaking freon out, electrical issue, pressure switch, compressor failing, desiccant bag restricting flow from juicing the system and never pulling a vacuum on it, cooling fans not working at speed or correctly, partially blocked condenser, etc etc etc…
You need to use manifold gauges to see what the system is doing…
I expect the proper course is to remove the HVAC box under the dash and replace all the doors, actuators, and plastic links inside. Then reinstall the box, hire an A/C specialty shop to evacuate the refrigerant, install the correct amount of new refrigerant, test for leaks and that all the pressures test correct. Big job for sure. If you are diy’er inclined you can probably renew the under-dash box yourself if you can free up 2-3 days in your schedule.
Thank you this was helpful.
George, thanks a lot for the reply. Although I could set aside 2-3 days to pull the box myself, I know going in it’s not going to be an enjoyable project. So I’m weighing that against what it might cost me labor-wise to have a shop do it. The AC shop I went to said it takes them 8-9 hours at a rate of $134 / hour, ~$1250. They also told me they don’t do those jobs anymore unless I’m willing to come in during the fall/winter months when they are slow.
If the suction line from the firewall is not cold to the touch, you have an a/c plumbing problem: low refrigerant level, weak compressor, inoperative condenser fan etc. Warm air on one side of the dash is a common indication of a low refrigerant level. If the suction line is warm, the blend doors are unlikely to be the problem.