Heisenberg

Makes sense to me. I'm just not sure how I can relate it to the fact that it happens when I'm stuck in traffic? Could it be that the high ambient temp makes the cycle more frequent and that makes the Expansion Valve freeze faster since the compressor runs longer?

Once I have this figured out I will post the solution here. If not, I guess I just have to mask the issue by making the condenser fan run all the time during this high ambient temp condition.

holmesnmanny

When the expansion valve goes bad it starts failing to open, which causes itself and evaporator to freeze up.

Just to be clear, i'm not certain its your cause, but normally when the system is working, then just shuts down, its likely the expansion valve is the source.

slowcivic2k

I'm going to suggest your own thread if you want to warrant a response from me.

The compressor circuit and its controls are independent of the ECM. The only PID the ECM looks for is the A/C request, in which case it will increase the idle speed by a set amount. If you are experiencing a run-away style idle, A/C is not your problem. The idle increase is arbitrary and is non-linear in nature.

In an expansion valve system the equalization of pressure takes hours, not seconds. A soon as the cooling load is released, the system goes into stasis if you will. An orifice tube system will balance very quickly, but no Honda uses this arrangement.

Poor cooling in higher temperatures are caused by a few issues:

1: Cooling system capacity. Honda does not design enough cooling in a 100 degree day with near 100% humidity. Understand that and read my previous information.

2: Insufficient air flow and too much refrigerant will also cause a problem. These problems when severe can cause engine stalling due to the excessive load. This also validates an engine that does not increase idle in response to cooling load, it is arbitrary.

Changing an evaporator is a stop gap solution. Increasing cooling efficiency in the evaporator will only make the condenser work harder, along with the compressor. All of these parts in a factory settings are designed to work in harmony to a point. If you read my thread in general you'd know that.

If you are experiencing problems way out of whack or cannot explain them fully, somethings is not stock, or not within factory spec. If you are creating a hybrid system, expect problems, and also, complex solutions.

Heisenberg

I apologize for hijacking your thread. I couldn't start mine since I'm a newbie to this forum. Thought this was the best thread to get opinions as you seemed very good with A/C systems.

I was able to solve the issue. Here's what happened. I noticed when the sudden rise in idle RPM happens, the fan is always on but the clutch is seized. Shouldn't happen right?Because those two should run together. So I checked the thermal protector and there you go, it tripped. Obviously compressor got too hot. I didn't changed the thermal protector right away, simply because I believe it's just doing its job. I began to suspect the A/C thermostat in the evaporator and observed if my A/C is still cycling on/off. Nope. So, for some reason the A/C thermostat failed, and was never tripping the clutch. I know understand why it was ice cold when the car is moving. Compressor is running all the time! It doesn't overheat because of the outside air which somehow is able to cool it. But during heavy traffic, the ambient temp on the engine bay and operation heat is just too much for the compressor.

You are right, as per the circuit diagram, the thermal protector is independent and the ECU wouldn't know if it tripped. So because the A/C switched is still on, the RPM is still high. I get the sudden and not gradual rise in idle speed because the protector trips.

Thanks for your and holmesnmanny's help. Hopefully this is the same case with riyazhyder and he's able to solve it already by this time.

SDPGreen

Hello SlowCivic
& the rest.

My 1998 civic ex's AC worked fine until the compressor started making ugly noises. Not knowing AC, it sounded like a bad bearing to me (removed the belt - noise stopped; no AC, obviously).

Guessing that meant it's time to replace it. (I've had the car for 7 years, 60k miles, so the AC is AT LEAST that old)

Reading some threads here, I believe I should replace the filter/drier too, and the expansion valve.

Does that sound right to you so far?


I have some mechanical skills, but only basic tools & a driveway to work in - and no refrigeration experience.

I enjoy working on my civic, and like to avoid spending any more money at a garage than I have to.

How much of this job do you think I could take on, without buying the charging tools, etc?

After reading your post (& others), I'm a bit hesitant - seems complex, with plenty of steps that could be missed, or not done correctly.

Assuming that I identified the correct parts to be replaced (above), I may just take those parts to a garage and ask them to install & charge.

If you believe I can do a portion of the replacement myself, and save some money, I'll probably follow your advice.

If I do ask a garage to install the parts i bought, what do you suppose a reasonable amount of time for them to quote would be?

Thanks a lot for any advice, Team Honda!!


BTW - below are the parts i bought - all from Amazon.
My civic has 160,000 miles on it - I'd like to get a couple/few years out of the AC, but I can't justify the cost of OEM parts all the time...

UAC CO3057AC Compressor
by UAC
Price: $117.98 & FREE SHIPPING

TOTAL
$46.34
Denso 475-7503 Expansion Valve

Four Seasons 33595 Filter Drier

Former User

Was the noise only present when the A/C was turned on (compressor clutch engaged)?

SDPGreen

Thanks for the reply, RonJ.

I'm 90% sure the noise existed regardless of whether the AC was on or not. It was definitely a bit intermittent - I didn't notice a definite pattern.... I seem to remember it being loud when the car started, & then would get less loud, but would come back seemingly randomly.

Sorry that I don't have my observations more dialed in. I should of been paying closer attention.

Former User

If this^ information is accurate, then the problem may be a bad idler pulley or bad compressor clutch pulley, rather than a bad compressor.

SDPGreen

That sounds better than the 4 hrs labor I've been quoted to put in the parts I bought... labor is EXPENSIVE around here!

I'm assuming if those are the problem, the best fix is to address those - or is it a good idea to just replace the entire compressor, once I'm that far into it?

Is there some troubleshooting you recommend I do to narrow down the problem before I look into how to repair a bad idler pulley or bad compressor clutch pulley?

Thanks!

Former User

Reinstall the belt and check whether noise is there without A/C being on. If so, pinpoint noise to idler pulley versus compressor pulley/clutch.

SDPGreen

OK, thanks, will do tomorrow. Pretty sure it will make noise all the time.

Looks like the pulley & clutch are right next to each other - any tricks to differentiating which is making the noise? Or am I missing something...

Former User

Have you ruled out the idler pulley (highest pulley in diagram)? To pinpoint, go to Harbor Freight Tools and purchase their engine stethoscope. Use it to pinpoint the source of the noise.

SDPGreen

Oh, now I see. Idler pulley is an entirely different thing. Thanks for the diagram.

I hope to diagnose tomorrow.

I'm considering replacing all three parts anyway, since I bought them & since the AC is likely stock, from 1998. It was cool enough, but not freezing... maybe getting less cool each summer.

In which case how much of this job do you think I could take on, without buying the charging tools, etc? & what would be a reasonable number of hours for a garage to charge?

Thanks.

SDPGreen

The noise exists whether or not the AC is turned on. Still not exactly sure where it's coming from.

Former User

Click the link.

slowcivic2k

I have replaced many idler pulleys on a lot of cars. To pinpoint the noise you will need a stethoscope. It is one of those tools that will pay 1000% returns. Most A/C bearing noises can be grouped into a few categories:

1: Engine running, A/C off, and there is horrific noise. Most idler bearing failures will produce a deep groan without the A/C on. The key is the deep groan sound, and the sound it produces is dampened somewhat by the engine. This noise can get deeper with the A/C on, and can produce a squeal. A squeal with a properly tightened belt is the idler bearing 9/10 times. Verify your source though, every car is different.

2 Engine running, A/C off, and there is light metallic scraping. This is usually caused by a broken or "relaxed" pressure plate on the A/C clutch. In short, your clutch assembly is either out of round, or has otherwise distorted to such a degree that it is contacting the A/C pulley without the system being turned on. This can happen to any car, but GM cars are the most notorious.

3: Engine running A/C on, and 1 and 2 both change tune. In the case of number one, the load placed on the belt may increase or in a few cases, decrease the noise from the bearing. This is why the stethoscope is invaluable. In the case of number 2, the noise will normally disappear entirely. This points to the clutch itself. The A/C pulley bearing may also be suspect in any of these instances, again, the stethoscope is your friend.

SDPGreen

Thank you both.

Very nice diagnosis flow, Slow Civic, thanks.

I think it's case 1. I'm going to research threads re. the idler pulley now.

fishnazi

I'm about to install a reman compressor, and new drier, condenser and expansion valve in my '00 Civic. The compressor failed some time back (while son was using it in Vegas); there's a quarter-sized hole in the case. I've flushed the lines and evaporator with Dura II solvent using the compressed air kit. I checked the lines and evaporator with a hand vacuum gage and they seem to hold (I plan to have a shop do a proper vacuum test and charge the system).


Based on the assumption that there was no leak of refrigerant prior to the compressor failure, what culprit is likely to have caused that? The pressure switch? How can I bench test that? I'd like to know before getting the system up and running.

slowcivic2k

Physical damage to the compressor is usually caused by road debris striking the unit itself. This is the first time I have heard of damage that severe to the unit causing the damage to describe. An overcharged system can cause that type of damage sure, but in my experience HIGHLY unlikely. A hand vacuum pump is worthless except to find the largest leaks possible. I'm not sure if I even want to know how you adapted a hand pump to the A/C system in the first place. I personally would like to see pictures of the compressor. If this type of failure did occur due to an unforseen pump malfunction, it needs to be published and documented.

I'm going to start by asking why you replaced so many parts. Were all of these parts damaged? Was there evidence of contamination in the system?

So long as the replacement parts function, and you re-lubricated the system properly, and replaced all required seals with ones that seal properly, I don't see why it wouldn't work.

Testing the pressure switches while installed can be done, but requires extreme attention as during testing of the high pressure switch, you can vent refrigerant. I do not condone nor do I support this.

Please create a thread in the Tech/Misc forum, this post has no relevance on this thread itself, and should be addressed as a separate issue. You can PM me with your thread information.

v6junkie

Hello, noob here. sorry if you already clarified this, but is the chart for temperature and delivery pressures to be assessed at idle or at running speed? When I increase the RPM the delivery pressure rises and intake pressure falls. Is this normal and which pressures do I use to gauge proper operation? Thank you for your excellent review and help.

fcbspain

i just learned in 10 minutes of reading more then hours of searching google thank you my element overheats with ac on in summer

slowcivic2k

The test should be performed at idle for the chart to be accurate. I specify another test speed, usually 2500rpm or so, to stress the system in the stationary position, because it is obviously not feasible to have manifold gauges hanging out at 40mph. The higher speed test I use helps me identify things such as the system going into a vacuum (expansion valve, low pressure switch, etc), excessive high side pressures (condenser fan problems, etc) since the system will work harder as the compressor speed increases.

PatrickGSR94

iTrader: (1)

What's up guys, haven't been on HT in forever!

I did an overhaul on my wife's 96 Corolla AC system back in 2011 after the compressor on that car grenaded. The whole clutch assembly just destroyed itself. I replaced the compressor, receiver/drier, and all the o-rings, pulled a vacuum and charged up the system with oil and refrigerant. That car's AC still works great to this day.

My 94 Teg's AC has been rather weak so far this summer. Nothing has been done to that system since I had the system recovered and recharged back in 2008 so that I could disconnect the evaporator underneath the dash and replace my heater core. So 8 years now. Today I'm pulling a vacuum on the system and recharging it up from zero. Hope I don't blow up anything in the process.

PatrickGSR94

iTrader: (1)

So yeah, I pulled a vacuum on the system, put in the specified 24 oz of refrigerant (2 full 12 oz. cans, just straight R134a stuff from Walmart for $5 a can, no additives) and DANG!! Car blows some COLD air now! Awesome!

Jamesflo

iTrader: (1)

Ok guys I really appreciate the help. On Tuesday I will have time to take it to a different shop and I will get you the low and high readings