2005 Accord EX V6 with 120,000 miles. An independent shop replaced my compressor 3 weeks ago and the AC seemed to work fine until we had a very hot day (over 95 degrees) and the AC started to blow hot after a 15 minute drive, then after a little while back to cold. It seemed to work as long as the car was traveling at speed but as soon as it came to a stop/idle it would blow hot and then the compressor would fast cycle, on,off,on,off.

I took it back to the shop and they tried to evacuate and recharge the system 3 different times but it turns out they were trying to put 1.6 lbs in it when it only takes 1.1 to 1.2 lbs per the under-hood sticker.

I'm fearful they overcharged my system originally when I had the compressor replaced and the problem just surfaced when the temps got real hot out? Is this even possible?

 

Is the issue still there?

When the ac is on, are both cooling fans running?

 

I couldn't do a long drive yesterday after leaving the shop but for the 30 minute drive it worked and continued to work while idling in the garage for 5 min or so.

The condenser and radiator fan do come on with the compressor, replaced the relays under the hood fuse box when I was trouble shooting the originally problem. The fans turn off with the compressor but I believe its supposed to that though.

The engine temp is good, the gauge stays just under half all the time.

I will drive the car today and see if the problem is still there.

 

The exact charge that your system calls for on the name plate must be weighed in with a scale. These systems are exact charges. If you go over the symptoms you are experiencing will occur and eventually will hurt that new compresser.

 

Ok, I've been able to run the car a lot this weekend and whats happening is the AC always blows cold and the compressor cycles properly while the engine is warming up. Both fans run with the compressor during this time but when the engine reaches full operating temperature the compressor no longer cycles? It will run constantly, air is still cold and both fans continue to run all the time, the radiator fan stays on high speed. Strange.

As soon as I turn off the AC the fans turn off and the radiator fan comes back on periodically to cool the engine.

Something causing the compressor to stop cycling when the engine is hot. Any ideas before I take it back to the shop. Thanks

 

Under some conditions, the compressor will not cycle; high external heat load and humidity. It simply takes all the system can do to provide cold air.

Use of fresh air instead of recirculate will increase interior heat load and humidity to be overcome.

good luck

 

Thanks for the reply. A couple of things to mention in case it helps. I live in Arizona and have no humidity and the AC would always cycle for all the years I had the car.

Somethings not right, having my AC stop working after getting a new compressor and then finding out the were overcharging the system has me concerned.

 

You will have to measure pressures and compare to operating chart from Honda to know if system is overcharged or perhaps has a faulty component such as thermostat.

A faulty thermostat would cause AC to run continuously but vent air outlet temps should be really low, perhaps < 30F.

good luck

 

I suspect that the high pressure control may be coming into play here. When the system has to much refrigerant it will still cool but will begin to loose it's efficiency as the pressures rise in the system. Ask these people that repaired the Ac how they charged the system. The only exceptable way is to weigh in the charge to the oz. Any more and it will cycle on high head pressure .

 

They were using the Robinair 34700Z Air Conditioning Exchange Machine, it turns out the book they were getting the information from was telling them the system took 1.6 lbs. After they told me about the issue they were having I pointed out the sticker in the engine compartment that showed the correct amounts.

Then they took the refrigerant back out and recharged it to 1.2 lbs. They told me to monitor how its working and report back this week if I continue to have any problems. I'm also trying to figure out what caused the AC to suddenly stop working in the first place after using it for 3 weeks.

I should point out that I trust the shop in that they appear to be honest people and I don't believe they are trying to screw me over, but like I said I have my concerns now.