Hi all,

I've been reading here for a few years fixing tiny issues as they come up. Wonderful bits of info here that are all accessible with the search function. However, I've been searching for a while and can't find anyone else here posting about my issues:

Last week the AC was just not blowing cold. The AC indicator light would turn on with the button, but the compressor clutch and fans would not turn on. I checked the low side refrigerant pressure and it was low. I added a tiny bit of refrigerant, and the clutch kicked in, so I continued with an entire can of refrigerant, and it got up into the acceptable range. But it was still a ways from nearing full when the first can ran out. So I tidied up and went back to the FLAPS for another can, and the AC blew nice and cold all the way there- great!

On the way home (one mile each way) I noticed a clunk happening every 10 seconds or so. As I pulled into the driveway, my girlfriend asked about the clunk she heard. Hmmm. As I prepped the second can of refrigerant, I noticed the compressor motor and fans cycling every 10 seconds, and clunking with each cycle. I didn't add the can- but I feel like the compressor is cycling way too quickly. I wouldn't have noticed, except for the clunk.

Should I be worried about the sound?

Should the compressor be cycling on and off so quickly?

Thanks everyone,
Rob

 

Some cycling is normal.

Without looking at your gages (both high and low sides) any information supplied is just a guess. If the R-134 level is low that will trip the low side level sensing . If the r-134 level is high that also will trip the high side sensing. Both will cause cycling.

I would not add any more R-134 and see what happens when it gets hotter outside. If it cycles more when the OAT is higher, then you have too much refrigerant in the system and are tripping the high side pressure limit. If it cycles less when hot then you are slightly low.

If you are happy with the cooling the way it is now then just leave it alone.

Here are some guidelines. The pressures vary with outside temperature.

With the fan on the highest setting and maximum cool on the temperature setting, the high should NEVER EXCEED 400 PSI on the hottest days.

Under the same conditions, the low side should run in the 40 to 45 PSI range. Most low side switches trip around 25 PSI.

The above numbers are based on my experience working on various R-134 vehicles and may not reflect Honda's exact specifications. Keep in mind that most vehicle manufacturers do not specify pressures these days. They instead specify the amount of R-134 charge in weight.

I charge empty vehicle AC systems by weight. I still charge partially filled vehicles using pressure gages.

 

Wonder if the clunk is a bad compressor clutch. Can you tell where it is coming from?

The high rate of cycling could be a faulty sensor too. If I remember correctly, the fits Compressor is managed by sensors to prevent freezing in the lines.

 

Thanks for the input folks.

I'm not concerned about the cooling. The AC is blowing colder and more consistently than before. What bothers me is the clunking-

After letting it sit a day, I drove it again. Now:

Start the car and drive for 5 minutes with AC on, no clunking, moderate cycling, great cooling. After 5 minutes though, the clunk happens with every engage and disengagement of the compressor. I'm not sure if the sound is from the clutch or compressor itself.

I do notice less clunking/cycling with the AC and fan on 1-2, and more clunk/cycling with the AC and fan on 3-4.

I will test it at night (60*f ambients) and daytime (90*f ambients) this week, will that help?

I don't have a high side gauge, so I'll probably be taking it in to be tested if I can't figure this out. Sound like the smart thing to do?

 

Do you know how many ounces of refrigerant were in each can? Did you use the kind that has sealer in it? Do you know how much oil each can had in it?

Some cans are 19 ounces and have 1-2 ounces of oil or sealer. I recommend staying away from sealers

Knowing that will help so we can consider how much refrigerant you may have in the system now.

Refrigerant isnt consumed by the system. If a vehicle comes to the shop and is low, one of two things have happened. The customer has released or recovered refrigerant during some kind of service to the vehicle or it leaked out.

Your system most likely is leaking since you didn't mention releasing any refrigerant. The clunking may be from an overcharge. The reduced clunking may be because some of what you added has already leaked out.

Time will tell if it soon stops working again.

The missing info here is what the low and high side pressures are and what ambient temp and humidity you are reading the pressures at. We also don't know how much refrigerant you started with. Its best to recover, evacuate and recharge to spec and then read pressures if you have the equipment.

If I were charging a system without gauges, I would read the evaporator temp and charge based on the temp of the lines at the evaporator and not the vent output temp. At least you are looking at a real value that will change based on what you add and not just the low side pressure on the can gauge.
.

 

I'm with 2010FitSport on this but without hearing the clunk and seeing the pressures, It is all a guess.

 

I just wanted to wrap this up and mention that I did eventually resolve the issue- I hope this helps someone in the future. My low-side gauge from O'Reilly's Auto showed MUCH lower than the low-side gauge at the local dealership where a friend now works. He found the original leaky fitting, and took care of refreshing everything by the book. So it was overfilled, by quite a bit actually, even though the cheap gauge didn't say so.

Live and learn, I guess, and don't buy cheap tools.

ab3