CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Can't recharge AC System

Hello,

I have a 2008 Honda Accord that is not blowing out cold air. I first tried doing some research and purchasing a canister of R134a. I had an existing hose and gauge from my dad from recharging the AC on another car successfully. I turned on my car, turned AC to MAX, verified the compressor turns on, shook the can, connected the canister to the hose with the valve up, and then connected the hose to the low pressure valve on my car. After connecting the recharge kit to the car I see that the gauge says 0 PSI. I turn the valve and turn the can and get no change. I tried 3 canisters and got the same result. I tried purchasing a new hose and gauge and the result is the same but when I connect it I see 100 PSI. After driving the car for an hour and trying again the same gauge has the needle in the middle between 0-100 PSI. I can verify that the compressor turns on by hearing it turn on after pressing the AC button on and off. I can verify the self-sealing canister is letting out gas by hearing the pressure after having the valve up, the hose disconnected from the low pressure valve on the car, and then twisting off the canister.

I decided to setup an appointment with the local Honda dealership but it is going to be about 2 weeks. I am wondering if there is something else to try or how I can verify if the problem is located somewhere else. I am thinking about trying to purchase a can of A/C Pro and see if I have a different result, or possibly purchasing a vacuum pump and manifold gauge set for further troubleshooting.

Any advice is appreciated, thanks.

Equipment used:
R134a: https://www.amazon.com/gp/product/B0888RXBXM

Hose and Gauge: https://www.amazon.com/gp/product/B07MM97MLP

You don’t need a dealer for this . Just find an independent AC shop .

2 Likes

Ok yup I have a few around me that I can take it to. Depending on the price I may just do that.

We tend to discourage people from working on their A/C systems here. Without the right equipment and knowledge, it’s possible to damage the system and possibly even your eyesight.

3 Likes

Ok I understand. Are there any good training series or books you would recommend for learning or getting certified?

Well, if compressor clutch is engaging like you say then you should feel cool/less cool thru dash vents when you turn ac on/off. The low pressure side of system routes Freon thru accumulator and back into compressor. The line should feel cold and be sweating if it is working at all. So, compressor is on but you have no cool lines anywhere in engine compartment? Compressor line to condenser should feel warm. Cooling fan should be running. That’s easy to see/check

  1. Compressor is on.
  2. Rad fan is running.
  3. Evap line is cool.
  4. Dash fan is running

Great, thanks for the help Cavell.

  1. My assumption that the compressor was on because of the noise I heard is false. The noise is actually the radiator fan and A/C condenser fan turning on and off. I will check the clutch and see if that is moving on the compressor.

  2. The radiator fan to the right and the A/C condenser fan to the left are both running when I turn on AC and MAX AC

  3. The pipe off of the low pressure service valve is not cool when the AC is turned on. Which I assume goes from the evaporator >> accumulator >> hose with low side access port >> compressor.

  4. The dash fans are running and air is properly traversing through them.

I will check the compressor and the line from the compressor to the condenser.

Why , if you are not going to do that for a living no need to pay for annual license fees. Also how often does the average person need to do AC work enough to justify the equipment.

2 Likes

Is compressor clutch engaging? Simple enough.

A recovery machine alone costs $4,100.

2 Likes

You need to be certified if you service other peoples AC systems, or if you want to purchase R12 refrigerant.

That’s why you can purchase R134a refrigerant at Wally World.

Tester

Hey Cavell,

I tried checking the clutch again and I did not see it spinning. It is hidden down there a good bit so I went through some videos to be able to see what it looks like when it is working properly. It turned out that the clutch was not engaging on the compressor. This would explain why one of my gauge readings showed 100 PSI.

I found RB The Mechanic’s video on a tip to check the MG Clutch 7.5A fuse for the compressor and the 12VDC relay for the compressor. After replacing the 7.5A fuse with my spare I got nothing. Then after putting it back and swapping the compressor relay with the horn relay, the compressor’s clutch activated and my AC is working again!

I can verify it was that relay because now my horn is not working. I have purchased a new relay and will replace it on Monday. My car is now blowing out cool air, just in time because this week I will be back in the office after a few months WFH.

I will monitor it now and hopefully there isn’t any electrical problems with the system that may have caused this.

Thanks so much for your help!!!

RB The Mechanic - Video on checking the fuse and relay on a Honda Accord

AutoZone 12VDC relay for horn or compressor
AutoZone - Duralast Relay 20742

Fuses that I swapped - 2008 Honda Accord underhood fuses - compressor relay on left - horn relay top

Fuse and clutch pictures