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1995 Accord AC compressor won't cycle
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gunl
New User
Jul 5, 2014, 12:22 PM
Post #1 of 9
(1971 views)
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1995 Accord AC compressor won't cycle
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1995 Accord, V6, 150K miles.
Bought car used. Great shape. AC didn't work. Pushed Schrader valve and released very little pressure ... system was essentially empty). Hung gauges. Held vacuum at -22 in Hg for over an hour. Charged system with 22 oz 134a (recommended charge). When charging system, the compressor was off until about 6 oz of 134a had been loaded, then the compressor kicked in. It will not cycle ... it just keeps pulling vacuum. Got the full charge of 22 oz installed.
When the car is off and the system is left to equilibrate, H/L gauges settle out at about 95 psi. When I start the car and turn on the AC (low fan setting), the compressor kicks in immediately and never cycles off. The system finally equilibrates at about -20 in Hg on the low side and about 150 psi on the high side. There is no cooling in the cabin.
I'm in the garage with outside temps at 90F.
Any insights would be appreciated.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 5, 2014, 12:39 PM
Post #2 of 9
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Re: 1995 Accord AC compressor won't cycle
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22Hg isn't enough vacuum (unless you are at an elevation of ~8,000ft.) and you really don't know why it was low or what happened when it failed before you.
Compressor may have thrown junk back when and fighting with blockage now. Could have kept pumping as it got too low on charge and burned up a bit but still doing something.
If moisture is enough or air from lack of adequate vacuum all bets off.
Locked up top is a temp/pressure chart or I'll find it. Your static of 95F tells of the temp of the system at that time. If below pressure (static) tomorrow just setting there there's a wild leak and find it now while anything is in it before continuing any more work. Right now running it you are hurting the compressor if not kaput already,
T
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gunl
New User
Jul 5, 2014, 1:43 PM
Post #3 of 9
(1958 views)
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Re: 1995 Accord AC compressor won't cycle
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Tom ...
Thank you for the reply.
I'm using a venture pump and -22Hg is as low as I can get. I'm at sea level. Live in Portland, OR ... lots of moisture. I have no idea of the history of the vehicle.
I will unplug the fluid sensor so that the condenser stays off and will monitor the pressure overnight.
Not sure I understand the 95F comment. Outside temp is 90F. The static pressure (after an hour with the vehicle off ... so the H/L gauges are equal) is about 95 psi. I will recheck this after letting the vehicle set overnight.
Found this comment on one of the other threads on this site ... "Usually if an orifice is completely clogged you'll have low high side and near zero low side pressure. Compressor can't pump refrigerant if there is no refrigerant getting to it." Could this be the problem?
It would seem that if my low pressure gauge is pulling to -20Hg that the compressor is working??? And I continue to be confused (doesn't take much) as to why the compressor isn't cycling.
I will post again tomorrow morning with the results of the overnight sit.
Many thanks.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 5, 2014, 2:49 PM
Post #4 of 9
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Re: 1995 Accord AC compressor won't cycle
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If you can only pull 22 in then you either have a bad vacuum pump or a severe leak. That just won't cut 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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Tom Greenleaf
Ultimate Carjunky
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Jul 5, 2014, 8:38 PM
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Re: 1995 Accord AC compressor won't cycle
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You meant "Venturi" pump like those that use compressed air? NO. Can't use those for A/C.
Actually it still should have done better but failed later so more is wrong. Again, most will fail due to a leak to be found. Not always easy and if it's been empty (hard to know if that was just pressure from heat when you checked or what now) it would have to be totally flushed out as the moisture if long time would have wrecked the PAG oil used in it.
As said check static pressure again vs the ambient temp around it. Should be close in PSI as temp in Fahrenheit at livable temps they are close. If lower it's a VERY fast leak.
No surprises as this car is now about 20 years old and plenty of folks don't want to spend the bucks for something you can do without. It just might cost a ton of bucks to make it work and last - concentrate on last as just one part probably will just fail and you'll just have wasted that, time and need more all over again and again.
This crap isn't so DIY friendly and is expensive plus equipment to do it costly.
You can rent a vacuum pump free ( so I'm told) but think you need lots more than meets the eye with this,
T
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gunl
New User
Jul 6, 2014, 4:27 AM
Post #6 of 9
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Re: 1995 Accord AC compressor won't cycle
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Pressure has dropped to 87 psi overnight but that is probably due to the temperature (PV=nRT for those of us who are nerds!). Am I wasting my time here? Do I need to get a better pump and start from scratch? If that is the case, should I be troubleshooting something before I start? The fact that the compressor draws the LSV to -20Hg ish and the HSV is 150psi ish suggests to me that the compressor is working but then again, I am a novice. From another post on this site, a response included, "Usually if an orifice is completely clogged you'll have low high side and near zero low side pressure. Compressor can't pump refrigerant if there is no refrigerant getting to it." Could this be the problem? Should I be checking for a blockage? Or is this where some moisture in the system could be causing problems ... water freezing in the orifice?
I appreciate your help. While I am a novice at AC, I am a fair shade-tree mechanic. Looking to expand my horizons!
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Hammer Time
Ultimate Carjunky
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Jul 6, 2014, 4:38 AM
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Re: 1995 Accord AC compressor won't cycle
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Yes, it was the temp change that caused the pressure to change. Static pressure has no relationship to fill level.
You need to stop getting ahead of yourself. Until you can get this thing to hold 29" of vacuum, you can't go any further. If it's a leak causing this, you have to find it. If it's just a lousy equipment issue, then that needs to be corrected.
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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.
(This post was edited by Hammer Time on Jul 6, 2014, 4:39 AM)
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Tom Greenleaf
Ultimate Carjunky
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Jul 6, 2014, 4:41 AM
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Re: 1995 Accord AC compressor won't cycle
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Quote"Am I wasting my time here?"
No you aren't listening. IMO this isn't for you at all. A day ago you had static pressure of 90+ PSI and now 87 PSI! It has a bullet hole leak. Some will hold vacuum but not pressure or certain temps they blow out and when checked it was tight.
Blockages CAN give you pressures you saw and just maybe frost clogged up someplace inside?
There's a lack of history posted as well. How long has it been down and any history of sealer. Cryo based sealers make quick shellac when exposed to moisture - essentially game over for anything the touches refrigerant in the whole system if that was ever used and awful hard to know except maybe evidence on a port or get help.
In fact you'd do well to get this at least diagnosed and a price to fix what then decide what you want to do as this just smells of spending tons of bucks and never finding out much or a real fix.
It's a risk of used cars in general and more so when A/C didn't work before you bought it - the person or place probably knew it was going to need a monster job but it was still a running car to sell so don't worry about it?
Your money and time,
T
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Tom Greenleaf
Ultimate Carjunky
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Jul 6, 2014, 4:43 AM
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Re: 1995 Accord AC compressor won't cycle
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Mistake - sorry. "Dropped to 87" not dropped 87 in total. Temp alone would do that. Rest still applies. This doesn't use an orifice tube but is listed as an expansion valve system. Clog would likely be there and temps would show but really shouldn't run it as it is too long. Put some oil (correct for car's A/C) in low side close to compressor if you even try again,
T
(This post was edited by Tom Greenleaf on Jul 6, 2014, 5:01 AM)
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