Air Conditioning qustion

[Tom]

I know this isn’t a subject that people like to broach much, but I fully understand the risks involved, and accept all responsibility, and need a bit of advice.

I have a ’96 Accord, which I recently picked up. The A/C isn’t working well. The compressor comes on, fans run, I can hear the air door hitting the stops when I move the temperature control. It wasn’t really cooling at all though. The previous owner indicated that there was a slow leak, and her father would always add a can of freon every summer to keep it going.

I checked pressures, the were low, with the low side pulling a vacuum, and the high side being under 100 psi. I went ahead and added a can, which brought the low side up to about 20 psi, and the high side close to 225 with ambient temperature at 80 degrees, and humidity around 80%, engine at 1500 RPM, and center vent temp just barely under the 80 degree ambient temperature.

The high side pressure seems pretty high to me for the temperature and humidity, and obviously the center vent temp is very high. There is no visible debris around the condenser, and driving the car at highway speed didn’t make a big difference. Center vent temps in recirculation mode, with windows closed only yielded a 10 degree difference between ambient temperature and vent temperature.

Obviously, something is amiss. I wonder at least to some degree, if the system just doesn’t have air in it from years of being topped off, and have considered having the system evacuated, drawing a vacuum, and recharging the system, however . .. . . I happen to have a condenser, evaporator, discharge hose, and liquid hose that are less than a year old, which I removed from my ’94 Accord. I also have a brand new expansion valve.

So then, my question is, considering the age of this car / AC system, is there any reason that I should recharge the system as is to see if it will work, as opposed to replacing the condenser, evaporator, expansion valve, and hoses, throw in new O rings, and then vacuum it and recharge it.

Topic

[Arthur Fieser Jr]

If it’s already leaking you might as well just fix it instead of trying to keep a dying system working just a bit longer. I’d just replace it all then vacuum and charge

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[Tom]

That was what I was thinking, but then wondered if there was something that I wasn’t considering.

[Tom]

Time to post a follow up here.

I couldn’t get my brain past the fact that I had 200 plus PSI on the high side, low pressure on the low side, and what appeared to be no cooling. It just didn’t make sense to me . . .. . until . . . .

Today I was driving my wife to work, and noticed that with the A/C turned off, temperature knob all the way to the cold side, and set to fresh air with the fan off, I was feeling hot air coming through my vents. It wasn’t terribly hot outside, at least not THAT hot. I flipped the temp knob back and forth several times, and could clearly hear the air door hitting the ends of it’s travel. I then opened the hood, and checked the coolant valve. Indeed, it was moving, but not a lot, so I reached down in there, and turned it towards it’s closed (pointing forward) position, and surprise, it was able to move another quarter of a turn beyond where it was when the temp knob was at full cold.

Next surprise, though it still doesn’t cool a lot sitting still, at 40 MPH it will blow 40 degrees at the vent. The temp still rises to near 60 when the car isn’t moving. The condenser fan looks like it might be running a bit slow, so that is something to consider, but the seemingly too high pressure on the high side is also something to consider. I still think that there may well be air in the system from being topped off many times, and that may be contributing to the high pressure, and poor cooling performance at low vehicle speeds.

Now that I know the system is working, as soon as I have the time, I will install the evaporator, and condenser that I have, as well as the new expansion valve, and hoses I have. While I am at it, I will replace all of the O rings, and then properly evacuate, and recharge the system, and I assume at that point, I will be good to go!

[Tom]

The further I go, the more I learn 🙂

I was thinking this morning, and thought that I remembered wondering if the condenser fan was working properly when I was working on the system. It seemed to me at the time as though the fan didn’t appear to be running at proper speed, so I fired up the engine, and AC, and watched the fan. Turns out, not only was it running pretty darned slowly, but more importantly, after the first minute or so, it just stopped working all together. Out of curiosity, I tapped the relay a few times, and the fan sputtered to life momentarily while I was tapping the relay, so I guess a new condenser fan relay is in order. I suspect that the system will cool MUCH better at idle once the new relay is in place.

[Arthur Fieser Jr]

I love hearing progress like this. Keep us informed

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[Tom]

I swapped the relays for the primary cooling fan, and the condenser fan. Still, the condenser fan was the one that sputtered and died, so that ruled out the relay as the culprit. I next went to playing with the wiring, that didn’t produce any results, so I tapped the fan blade. Ding ding ding. Every time I touched the blade and pushed it forward a bit, the fan sputtered to life, then died again. Half a can (not really quite that much) of silicone spray got it running for a bit. A/C was then able to maintain around 50 – 60 degrees depending on outside temps, even with the car sitting still.

At this point, I just received a new condenser fan motor in the mail yesterday, as well as a set of new O rings for the system. The fan motor will go in either today or tomorrow, and then I need to wait for a day when I have the time to tear the rest of the system apart. I now know that with that fan installed, everything is working properly. I am reasonable confident that it is a bit under charged, and that it has air in the system, leading to higher than normal operating pressure on the high side. This gives me complete confidence that once I replace the evap and condenser cores with the new ones I have (as well as the expansion valve, since I already have that as well) and O rings, and properly charge it, I will have wonderfully cold air just in time for the summer heat here in NY.

I will post again once I’ve finished the job, and everything is working as it should.

[Greg]

Most of the time when people add a can of Freon they put in way too much and it has the opposite effect on what they are trying to achieve.
Please do not vent the system to the atmosphere and do have the system properly evacuated before you start replacing any parts.

[Tom]

When I added the can (I can’t speak for the reported yearly topping off that was done before I got the car) the low side was in vacuum, and high side was a bit under 100 PSI with literally no cooling effect happening. After adding the can, the low side is still at only 20 PSI. I am pretty certain I didn’t overfill the system. I stopped where I did because of the higher than expected high side pressure, and only added the can because I wanted to verify that the system was indeed working before putting time and effort into replacing parts.

I do have a local mechanic whom will recover the charge from the system for me, and I always use him before opening any A/C system up for work.

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