Wankenstein

Purchased a '95 Civic last Friday and after an hour of driving the compressor no longer engaged. I tried several times for the next hour (long road trip) but, never engaged. A/C worked on two prior test drives of up to 30 minutes each. The cabin temp never got very cold but, not surprising for a 5th (and 6th) gen civic so I wasn't real concerned. Today (didn't drive yesterday) the compressor engaged again and ran okay for the 15 minutes I drove the car.

Seller said he and his friend (HVAC tech) replaced all a/c components except condensor and evaporator. They blew out a/c lines before install. He gave me reciepts of new a/c components.
Since the a/c system is closed, if it incurs a leak to a point where pressures are off and the compressor will not engage, is it possible for the compressor to engage again the following day ..as in my car's case?

From what I've read a partially or fully clogged condensor can prevent proper cooling return and cause the compressor to draw to many amps, overheat and trip the compressor's hi temp fail safe switch. Is this correct?
If, the condensor is the issue can it alone be replaced or is more involved?
Also from reading symptoms of failing/failed condenser are:
improper cooling and system not functioning.

ezone

see if power is still supplied to the compressor after it quits working.
Check coil resistance while it's not working


Quits after it gets hot. Works again after cooldown. Clutch air gap too wide. Check that.

Wankenstein

Thanks Ezone.
Clutch air gap too wide came up a few times as a possibility in the material I was reading through as well. Do you happen to know the spec gap? IIRC the air gap in my old 6th gen (Sanden) is .045 in. but not sure if it's the same compressor or gap used on this 5th gen.

Is this (quick read) info correct for testing: https://uacparts.com/Downloads/ClutchCoilTesting.pdf

ezone

Spec:
gap 0.5mm (1/2 mm) +/- 0.15mm
or 0.020", +/- 0.006"

coil resistance about 3 - 3.4 ohms
if it measures open, check if the thermal protector is open

.045" gap is too much...pull the outer plate off and remove a shim (if possible) and recheck operation?

Wankenstein

Thank you very much for the specs.
I haven't measured the gap yet. I got .045" from an ETCG video but. turns out that was a guesstimation.

I don't have much a/c experience and bringing it to a very knowledgeable, young mechanic that I was introduced to through the seller. I will bring the gap specs and resistance info to him. He's going to check pressures and dye test it for leaks. I am bringing it to him this Wednesday.

Any other possibilities given the symptom I described?

ezone

You could get the AC to quit, then push on the clutch plate with a tool and see if it will engage again. That proves it's still powered up and either the magnetism is weak or the gap is too wide. At high mileage they all wear and the gap gets too wide. That's the point it quits after it gets warm, works again after it cools off.

If it LOOKS like there's a full millimeter of air gap,
Remove the center nut or bolt from the AC clutch, take off the outer plate, remove shim(s) to reduce the excess clearance, reassemble and see if it works again.

Wankenstein

Okay will do. The compressor was new about 8k miles ago according to seller and the compressor receipt he gave me correlates. I haven't checked the stamp on the compressor so not sure if it's a Sanden or other (Hitachi ?) OEM brand or aftermarket. Price on receipt $300.

Another separate issue is gas is leaking from somewhere on filler neck only during fill-ups. Have you ever replaced one and if so, are they hard to do? Coudn't in service manual. Seller said he replaced a clamp where the cap/neck joins the filler pipe but, didn't fix leak. According to pic seems like it shouldn't be too hard to replace unless very limited space and/or tank needs to be dropped. If it's silmilar (7th gen) to video below looks pretty easy:



https://www.youtube.com/watch?v=MUdQ3CfHgfU

ezone

Ok don't just pull out a shim yet, if that compressor is that new. Do check other stuff first like power to the compressor when it quit. .
Not in my memory and probably too old for me to see here... but I've seen several 6th gen fuel tanks leak and pipes rot out, and Accords do the same.

Wankenstein

Alright.

Some forums research also leads to the solder joints for the a/c dash button on the HVAC controller board loosen or weaken and even though green light comes on the switch isn't making contact and the ECU doesn't engage compressor. Recommended fix is to resolder control board joints for a/c switch.

ezone

Diagnosis is supposed to be a methodical process based on inspection and testing, not random stabbing! LOL

I'd think you could push and wiggle on the unit and have operation come and go if that were the issue......But sure, open er up and dribble some fresh hot lead into it...see what happens. May as well check your main relay and redo the board on it too if it's original.

Wankenstein

Okay. Thanks again.

Wankenstein

Brought car to mechanic today and he hooked it up to his HVAC recovery, recycle and recharge machine. Pressures were fine and blowing 60 (normal for 5th gen?) degrees at vent. He pulled vacuum on it and recharged it (Seller paid) and said the system is holding vacuum well. He also banged on the dash near a/c unit a bit to check for loose connections/solder joints and the compressor stayed engaged. Vent temp after vac and recharged was 59 degrees.

He couldn't get it to mimic symptom in my initial post. He said (as well) that due to age/mileage of compressor that he the clutch/gap shouldn't be an issue. He thinks that when the a/c was installed 10k miles ago that it wasn't done properly or as thoroughly as possible and the aftermarket compressor is most likely weak/failing due to contaminants.

The seller said all new components with the exception of the condenser and evaporator were installed by his friend who's an HVAC tech. The seller also told me and the mechanic that all a/c lines, including condenser, were blown out with air and flushed with cleaning chemical prior to initial startup.

I drove 45 minutes on my way home and the compressor stayed engaged (normal cycles) and blew cold (at vents) the whole time. Whether outside in low to mid 70's. Mechanic recommends darker tint, park in shade and anyone's guess how long the compressor will hold up. He said that the a/c may get colder at vents during summer because outside (Florida) heat will raise high side pressures. On the drive home the a/c belt started squealing intermittently. Since I purchased the car I could occassionally hear a very short and very intermittent squeak from the left side of the motor but, didn't connect the dots to a/c belt. I will check tension on it but, possible this may be early sign of failure/seizure?

Mechanic mentioned that pulling vac on it also helps in lowering contaminants. If that is the case can it cause an already contaminated system to work more efficiently temporarily? Is there anything at this point (besides new system) that can be done to improve the situation or prolong compressor life?

ezone

59? If that's as cold as it can get without a significant heat load, it's not gonna be pleasant when it gets good and hot out there..

I'd expect 40-45, maybe 50 tops.
But an old system might not be able to get that low without a lot of money....


Get it running, feel the low side pipe coming out of the firewall. Is it waaay colder than 59 degrees?

Is the heater valve shutting off water flow when the temp is set at max cold?


Compressor? What were the pressures doing that would make one guess this?

Does the system have a new expansion valve?


Whyyyy belt squeal intermittently?
Loose belt?
Extremely high head pressure?


Oh god, I'm trying to diagnose it long distance again.

Wankenstein

Between owning this 5th gen and two 6th gens my personal experience is the a/c temps always struggle to cool on hot days and at best cabin temps feel cool but never very cold at night or cold outside temps. Google agrees: https://www.google.com/#q=92+00+hond...ot+cold+enough


Will have to try this soon. Seller told me today he installed a new heater valve less than 10k miles ago. During coolant pressure testing the other day I noticed the valve and hoses looked to be in newer condition.

I can ask the mechanic on Monday


Yes.

Not sure

I hope so

I hope not. Didn't even know that was a possibility and don't like the thought of it.

And much appreciated. Thank you.

ezone

I see a whole bunch of complaints about broken cars there LOL

Ya, the systems aren't overbuilt at all, the systems in the small cars are usually undersized for the amount of space that needs cooled......but the vent temps IMO should still be below 50 if your ambient temp is only 75ish.

You said your system is cycling the compressor off and on regularly? IF the AC thermostat is controlling the cycling, that would mean it should be in the mid to high 30s in the middle of the evaporator core......
How cold is that suction pipe?






I still want to tweak my car to lower a few more degrees before cycling the compressor off. Right now it cycles off when the evap temp reaches about 40-42F, I'd like to make it cycle off around 35-37 or so. I think it's purposely set high for a little gain in fuel economy and it's fine on a long trip where it has lots of time to cool down the cabin, but on a hot sunny day here the interior can reach 180*+ and when I've only got 5.5 miles to go between work and home it doesn't cool down the interior anywhere near quick enough for me. I know--- I want to defy the laws of Physics and make it do things that can't be done.

Wankenstein

Felt it and it seems to be much colder than 59 degrees.

ezone

If this is true, that means the evaporator core should be much colder than your 59 degree vent temperature.

Now....how can extra heat be introduced into the air flow within the heater housing?


Recirculation flap not closed, allowing outside air into the car?

Temperature cable mis-adjusted?
Water valve isn't completely closed in the 'cold' position?



Backtrack here a minute........If you fire up the engine from stone cold and turn the AC on immediately, does the vent temp reach much lower than 59 ...until the engine starts warming up?

Wankenstein

Only way I can say 100% is to put a temp gun or thermometer on it.

Removed glove box, key in second position, switched from vent to recirculation a few timesand can hear motor engaged and see movement of control arm. I read that to see if flap is closing completely the widshield cowl needs to be removed..correct?

[QUOTE=ezone;4719066]Temperature cable mis-adjusted?
Water valve isn't completely closed in the 'cold' position?

As stated the water valve is fairly new and I assume it was adjusted properly.. I texted seller and waiting for reply.

How long after shutting engine off to reach stone cold? I usually wait overnight.

ezone

If you think it's much colder than 59*, you're probably correct.


Meh, not really necessary for now. I just wanted to be sure it changes positions for now. You may be able to watch the door move if the glovebox is out of the way, but that's not necessary right now.

In the heat and humidity of summer, checking that it can close and seal might become more of an issue.

Right. I was looking for cold enough that there isn't any hot water circulating in the heater--- so you can tell if the AC can get much colder than 59*.
I'm thinking if the AC is really working good and your ambient temps are in the 70s or lower, the AC will get good and cold before the engine has had a chance to develop much heat. That could lead to a conclusion of hot water is still circulating in the heater when it shouldn't be (water valve isn't shut off).




Why assume?????
Feel the heater hoses. If you've had the engine hot, temp set to cold, and the AC running for a while--- but the heater hoses at the firewall are still screaming hot, that water valve probably isn't fully closed.

Note that engine compartment heat might make the hoses you feel rather warm, but they shouldn't be 180*+ scald your hand hot like the rest of the system.....the supply hose may feel warm but the return hose should not be hot....if that makes sense (it made sense in my head)

Check cable mis-adjustment. Check the cable moves and the arm actually changes positions when you change temperature from cold to hot.

Wankenstein

Makes sense.

Will report back tomorrow. Superbowl pregame trumps auto inspection at this juncture. I found this for very good a/c read: http://honda-tech.com/forums/tech-mi...oesnt-2900177/

Now I know why you were asking about pressure levels. The mechanic did rev engine a few times while watching pressures as well as during idle. I will ask him tomorrow what the levels were and what lead him to his conclusion of weak compressor and possibilty of contamination.

Attached heater valve adjustment diagram below. Does the HVAC contol unit need to be pulled out of dash to adjust?

ezone

I dunno...you have the instructions.


What I wanted to find out is whether or not the water valve is truly turning off the water flow.




You shouldn't need instructions on installing the whole kitchen sink just to check if the faucet is dripping. Right?

Wankenstein

I've read (various forums) some people thought their heater valve adjustment was correct, water shutting off but, temps were similar (60 F) at vent to mine. However, after re-adjusting according to service manual they got better readings.

Just spoke to mechanic and said high side readings during idle were inconsistent (needle jumping) and leads him to believe compressor may be contaminated/failing.

ezone

Ok.... I only wanted to make sure the hot water flow to the core is shut off.

Disconnect the cable from the water valve and move the lever with your finger? If it makes a difference THEN go through all the adjustment procedures (installing the entire sink LOL)


Vise-grips pinching the hose could accomplish the same goal of stopping water flow, but probably cause damage to the rubber hoses.

Hold RPM steady at 2000 for testing. Most compressors don't pump very efficiently when the engine is only idling.

Also....needle issue........if the high side service port is located close to the compressor it can show vibrations on the gauge needle especially at idle, it can sense every pulse as the compressor pumps at low speed.
If the service port were located 'after' the condensor in the system , you would not be able to see as much of the rapid needle fluctuation.

Wankenstein

Will do. Plan to work on it tomorrow.

I need to find an Ezone-esque local mechanic. So, should I bring it to someone else for a second opinion? I don't have HVAC gauges.

ezone

Nah.

Check out the water valve and see that it shuts off the flow of hot water through the heater core.

Wankenstein

Replaced right rear hub and it pulled off in one piece. Seems to be in good shape but, figured best to replace both rear hubs at the same time.
Tightened a/c belt..no more squeal but, didn't get a chance to drive it much afterwards. The short distances I drove the compressor cycled on properly.

I didn't get a chance to mess with the heater valve. I do think it may not be adjusted as best as as it could be. If, it turns out it the heater valve isn't the issue then what may be the next suspect?

ezone

Answer these two questions first:

If you let the AC system run for a while (2000 rpm-ish if necessary), does the compressor cycle off and on regularly?

After that compressor is cycling off and on regularly.....What is the temperature of the low side pipe coming out of the firewall?



Reasoning:
The system should cycle the compressor off when the core reaches around 34-40 degrees, then kick it on when the core temp rises a few degrees. Repeat endlessly.
That establishes the evaporator core itself is cold.

The pipe temp check can confirm the core temp, and confirm there is sufficient refrigerant charge (to a certain extent...i.e. if the refrigerant charge were too low, the pipe temp would not be nearly as cold)

After that is established......Vent temperature should be within several degrees of the core temperature.
You tell me where any extra heat is going to come from.

Wankenstein

Should have answers tomorrow, as well as doing the heater valve adjustment. Going to clean condenser with HVAC foam cleaner and water too.

I can't. Must be either heater valve or air vent/blend door on cowl not sealing properly.. as you already mentioned. I'm purchasing an infrared thermometer tomorrow for more accurate readings. Been wanting one for a while now and it's only 20 beans at HD.

ezone

It won't be the fresh air vent....that probably wouldn't even be an issue until it's hot and humid outside. (it's still in the low 70s there, yes?)

The only place heat would enter the HVAC housing is from the heater core....and if the flow of hot water is completely shut off that can't happen.


The rest of the checks were to try to figure out what kind of vent temp could reasonably be expected.

Now that you mention cleaning...I wonder how much debris might be caked on the blower side of the evap core?
I thought you said the condensor was new, it should be relatively clean?

Wankenstein

Yes.

Okay

How to check?

Condenser and Evap are the only parts that are not new. Not sure why the seller chose not to replace the condenser at the time...aftermarkets are $50. I'm sure not as good as OEM but, probably better (less contaminated) than a 20 year old OEM.