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97 Civic AC inop days works nights
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comnavguy
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Jul 19, 2010, 1:02 AM
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97 Civic AC inop days works nights
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97 Honda Civic AC works with ambient below 85 degrees at night, but at daytime with temps running 92 to 102 the AC will not come on at all. I have wiggled every switch, and every wire in the AC system that I can get my hands on - the clutch will not engage. At night when it's cooler, the AC will not quit unless I turn it off with the on/off switch.
Last night center vent temp was down to 38 degrees with ambient of 80 degrees.
There are 3 relays and I've swapped them to no avail.
I need some help.
Anybody got ANYTHING?
Thanks
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Hammer Time
Ultimate Carjunky
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Jul 19, 2010, 2:35 AM
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Re: 97 Civic AC inop days works nights
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A couple of possible problem areas are......... It has a thermostat control that should be under the dash where is can read from the evaporator. It also has a combination high/low pressure switch that needs continuity through is to run. The control head is always a possibility to be effected by outside temp too. The circuit would have to be traced down while it was not working.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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comnavguy
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Jul 19, 2010, 4:54 AM
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Re: 97 Civic AC inop days works nights
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Where is the Hi/Lo pressure switch? Also there is an AC dual diode on the schematic. Can you tell me where that's located.
There is a relay behind the glove box, and I don't know what it is. I was tracing the wires and time and heat finally got to me.
Thanks so far for the hints.
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Hammer Time
Ultimate Carjunky
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Jul 19, 2010, 5:08 AM
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The switch is in the left front, next to the power steering reservoir. The part behind the glove box is probably the thermostat module. It will be connected to a probe that goes into the evaporator. I was trying to post a wiring diagram for you but I'm using dial up here and it's just log jamming. I can do it tonight when I get home if you still need it.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Hammer Time
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Jul 19, 2010, 5:18 AM
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I was finally able to finish the upload.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
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Jul 19, 2010, 6:36 AM
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Memory is cooked but there's a strange problem for vehicles subject to dessert type heat days with plain engine heat in area shutting down compressor making it behave as if high side is too high. Doesn't happen where I am.
It is fixed by by-passing one of two cut outs for high pressure high temps. I don't have a clue which ones fix it or how it's done properly and safely right now. It was a topic that ACProf solved at the forum at my sign off.
ACProf lives in Phoenix. This was routine to properly and safely alter OE design for extreme temps with a problem if it is exactly this problem. All were temps exceeding 100F when it happened. That's air temps. Actual car temps, where it's parked, color of pavement those temps can be lots higher.
If I can find the thread in that site or you try it's a proper safe way to fix IF and only IF this is the exact issue. From memory (what's left) it didn't defeat any failsafe cut outs just took one of two that was placed wrong for those extremes and was fooled.
Please - don't change a thing without exact details of a proper fix which involves changing wires never suggested unless well engineered,
T
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Hammer Time
Ultimate Carjunky
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Jul 19, 2010, 7:41 AM
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You can see the thermal protector in the wiring right before the compressor but I don't know where it's physically located. I wouldn't be bypassing any pressure switches though.
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Tom Greenleaf
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Jul 19, 2010, 9:12 AM
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Haven't had to do this and never happened here as said. I belive the "thermal" shut down can shut down compressor from just engine heat so it's messed up by location on the compressor which is so tight in those and many.
Generally temp and pressure is an exact science. If you sense a temp you know the pressure and vs versa. However when temp is from another source it fools it and stays fooled at the higher temps. Compressor thermal switch would actually be cooler if it ran but they quit and stay quit till whole assembly cools down. If that and don't know that it's a flaw in design for locations. The HPCO should never be bypassed or course. I don't know of a TSB on that specific fault,
T
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comnavguy
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Jul 19, 2010, 9:56 PM
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Re: 97 Civic AC inop days works nights
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This is, indeed, one of the strangest.
NOW, I can't make it fail. It was 99 ambient today, and I ran this car through the paces, AC on, off, back on, relays switched, wires wiggled and everything I could think of to try to make it fail. If I had hair, I'd pull it out.
I'm going to work on the "bypass" thingee, even it it's only to prove where the failure ain't.
I appreciate the real wiring diagram.
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Tom Greenleaf
Ultimate Carjunky
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Jul 20, 2010, 4:14 AM
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">>If I had hair, I'd pull it out.<<" LMAO!
Do copy the diagram HT posted. Some things can disappear later so get it while it's good. As far as intermittent problems in general they do cause hair loss if any as you said.
Please don't mess with any wiring till you have EXACT details as this when I saw the frustrations from another site I was just the amazed on looker. As said ACProf was the one (near certain) who is a real physics professor in AZ specailizing in heat transfer and all that goes with it.
It gets over 100F actual air temp in the North-East and has this year for a few stretches. NBD - most folks love it to a point. It doesn't stay there long even during the day.
No matter for now and if it's working testing much of anything isn't going to be informative. I'll say that the relays can be heat sensitive and not make good contacts thoughout a vehicle but near always one at a time if toubles.
Off Topic: Took me months to find a fault that wouldn't stay broken and every thing when tested even when down (was power door locks) worked when down then they would work for a month like you had two heads so that ended the hunt.
Another whacked problem was A/C wouldn't work dependably because the clutch coil on a whole line of cars wanted engine running voltage exactly over 13.8 or wouldn't pull clutch to engaged - the fine not adjustable voltage regulator was the entire fault! Stuff happens. The temp extremes bring out the funky stuff.
Again - don't rewire anything. It cools or can so don't blame level of refrigerant charge yet. Checking pressures it ok but don't mess with the charge.
What you can do while it's working that would be helpful for any is make sure condenser is clean, radiator as well, fan(s) operatate properly and have good airflow unobstructed. Heat shield all in place - things like that should all be correct on any car anyway.
One more for now: Does engine temp stay normal in this? If even within norms if it can run on the higher ends of norms there's some radiant heat even against airflow raising temp of condenser too so A/C struggles that much more. They are designed (A/C) to shut down if pressures are too high which heat can do,
T
PS: Here's a neat link to who we call the GodFather of A/C (at least at that site) and good with whacked problems too....
http://acsource.net/...c.php?f=1&t=8352
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Hammer Time
Ultimate Carjunky
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Jul 20, 2010, 5:25 AM
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Good point about the engine temp Tom.
I know many Fords are programmed to shut down the A/C if the engine temp rises too much. Not sure if Honda does that.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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comnavguy
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Jul 22, 2010, 12:30 AM
Post #12 of 12
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Great info, even the off-topic stuff.
I did clean the radiator and condenser. The temp is stable and mid-scale on gauge, and climbs a little at stop lights. Swapped relays, and fans cycle as necessary.
Today, the AC is working as it should, and the local temp is still hovering around 96. I've ordered all three relays just to eliminate that possibility. And I'm not ready to do any bypass. That may come if nothing else works.
Thanks for all the help and suggestings. PARTICULARLY the schematic.
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