Auto A/C

1,491 Views | 16 Replies | Last: 1 yr ago by barnacle bob
barnacle bob
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2006 Honda Civic

A/C was working fine then just stopped blowing cold air. Blower works, it's just hot.

I checked all the fuses and relays, no problems.
There are two fans, one did not work (passenger side). The non-working appeared to be for the condenser. I replaced that and both are now working. A/C still hot…

Compressor and clutch turn.

Is there anything else I should check, or is this likely refrigerant/leak issue?

I don't have gauges, and I'm pretty much at the end of my skill set unless there is something obvious I should be looking for.

Also, would it be weird for two failures/issues here or could one failure cause the fan to fail?

I find it hard to believe there could be two failures in the system, but my knowledge is limited here…
Dill-Ag13
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If the compressor is not cycling at all when you have the A/C turned to full cold then your Freon is low and the low pressure switch is telling the compressor not to turn on because of the low Freon.

If the compressor is cycling and your A/C is turned to full cold then there is another problem that requires tools for more detailed diagnosis.
barnacle bob
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Thanks for feedback.

I had it diagnosed, compressor took a dive. They evacuated and re-charged.

I'm diving in and rebuilding the system this weekend. Compressor, condenser and expansion valve, o rings all around.

I suspect I could get away with just compressor, but most things I'm reading say change all down stream parts when doing a compressor. Is it best practice to do the system rather than just compressor?

Recharging was intimidating, but I spent some time learning about it, and feel pretty comfortable with that now.

A small shop is going to do a proper evacuation before I start anything.
MouthBQ98
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I just did this last weekend with my Honda Fit.

Replaced the condenser and the compressor. Ran flush through everything else with a bunch of compressor air to blow it out. New seals on the old lines, added a bit of pa46 oil, re-charged the system.

Also replaced the nasty cabin filter I never knew was in there, and cleaned out the cage fan blower.

Works great now.
coolerguy12
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What is this "proper evacuation" you speak of? You mean to tell me running the hose to a plastic bucket full of paper towels isn't sufficient?
txyaloo
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Have you considered paying the shop to properly refill it too? If they're evacuating your old refrigerant, you generally would only need to pay the labor and any net new refrigerant during the fill which for 134a would be the same as you'd pay to buy a vac pump, manifold gauges, refrigerant, and oil. If you only have 1 car, it's prob more cost effective.

Professional AC machines make life a lot easier than using a separate vac pump, gauges, scale, and refrigerant cans.
barnacle bob
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Good point txyaloo

I only considered buying the pump and gauges to pull a vacuum to make sure I don't have any leaks.

I'll talk to the guy and see if we can work something out. It's a small one man operation.

I'm really just doing this for the education. I'm reasonably handy and have most of the tools. This car is in otherwise great shape, strictly a short distance commuter, want to make it through the current auto market and readdress on the other side.
SECAg13
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The oriellys by me has a vacuum pump as one of their free loaner tools. You just make a deposit with a credit card and they refund you when you bring it back. Might be something worth looking into.
Bonfire97
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Quote:

A small shop is going to do a proper evacuation before I start anything.
As SEC mentioned, you can usually get a vacuum pump from the auto parts house if you buy the parts or the 134a from them. Also, tool rental places rent vacuum pumps. Here is a helpful tip to ensure you boil all the moisture out with the vacuum process. Do all of your repairs and close the system back up. Then, park it out in the sun all day. About 5pm, start it (AC off) and let the engine run up to temp, then cut it off. That will ensure the engine bay and interior are as hot as possible. Then, start the vacuum process. That will give you the best results.

Also, be careful about using R134a pressure/temperature charts that you find on the internet. Some of them seem to have ridiculously high pressures listed. As a datapoint, I was messing around with mine the other day (100F ambient) and the high side pressures I was reading off the OBD were between 190-220psi. That was with the door open and the blower on low. They would be slightly higher if the blower was on high.

Another datapoint - my "static" pressure reading on the high side early morning at 77F ambient and in the shade was 75psi.

I consider these normal readings, as my system is performing well (except for the faulty low pressure side cycling switch I am waiting on from RockAuto).
barnacle bob
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Thanks everybody, great suggestions and advice.

Last question (I think), how critical is flushing remaining parts in system? System in this case = lines and evaporator, all else is new.

Bonfire97
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Quote:

Last question (I think), how critical is flushing remaining parts in system? System in this case = lines and evaporator, all else is new.
I have always been of the train of thought that there is not much that can get past the orifice tube/TXV because you are basically dealing with a pinhole. That said, most of the trash from a damaged compressor ends up in the tubing between the compressor and condenser, the condenser, and the tubing between the condenser and the orifice plate/TXV. I would recommend:

While the orifice tube/TXV, compressor, and condenser are still out of the vehicle:
1.) Blow flush through the line from the compressor to the condenser.
2.) Blow flush through the line from the condenser to the orifice tube/TXV.
3.) Put it all back together. Installing a new condenser (like you are doing) is very important in a compressor damage situation like this - you can never get all junk out with a flush.

Others may disagree with my approach, but I think that eliminates any junk that could be on the high side of the system, and, as stated above, I don't believe much junk can end up on the suction side because of the orifice tube/TXV. I also don't like the thought of having "leftover" flush that may not boil out during the evacuation process left in the evaporator or accumulator.
lb3
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coolerguy12 said:

What is this "proper evacuation" you speak of? You mean to tell me running the hose to a plastic bucket full of paper towels isn't sufficient?
Are the bucket and towels just to catch the oil blowing out of the hose? I just wear gloves and just try to keep it off me and the paint.
barnacle bob
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I got everything changed out and flushed. The worst part was messing with the serpentine, just no room to work. No extra parts or screws, one lost socket behind the block

I charged, and I'm getting low side pressure but can't get high side within range. Air is cool, but not cold. I'm get 60 at vent.

I drove around for a while hoping it would pressurize, but still the same.

Compressor is turning and clutch is engaging. I pull a -30 vacuum and let it set for hour or so before charging, no leaks. The only thing that comes to mind is the high pressure switch, but that is just a guess…

Is there something obvious I'm missing, or time to call in the pros?

Silvy
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Are you sure you refilled with proper amount of refrigerant or did you just go off of pressure readings?
barnacle bob
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I tried to fill to volume, and verify with gauge. System calls for like 14-16oz range, I put one 12oz and then tried to use gauges to dial in remaining. The high side went up, but not in range. It's very possible I over filled trying to get high side up…
Bonfire97
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Did you purge the air out of manifold hoses before filling with refrigerant?

Please post pressure and ambient temperature readings using the following method:

1.) A/C on, A/C blower on 3/4 speed, recirculate mode, windows closed.
2.) Let run (idle) for 5-10min to stabilize things.
3.) Take pressure readings at idle and again at 1500rpm.

Also, let the car sit overnight and before the sun can hit it in the morning, take the static pressure on both sides (car off and before it is started). The pressures should be equal. You want everything the exact temperature as the outdoor temp. Please post that along with the ambient air temperature. If the static pressure is below the value for the r-134a temp/pressure curve, you can be certain that it is undercharged.

This information will help us to understand what might be going on.
barnacle bob
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Thanks Bonfire for the detailed instructions for diagnostics.

My gauges are very low end (cheap) I suspect that is the biggest issue here.

Time got the better of me and I had the shop that evacuated check and recharge. No issue found and it's blowing cold now.

It was 100 ambient when I finished and trying to cool, I could only get 60 at the vent. That may be the best I can do in the heat of the day. In the morning I'm temping 40. I'm calling it good.

I would do it again if I had to, it wasn't too bad. Took a solid day for everything, I lost one socket behind the block and got some new tools out of the deal, saved a good chunk of money, and learned a lot.

This is a 16 year old commuter that still presents well and has no other issues. Just trying to keep it alive until markets level out.

Thanks for all the advice everybody
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