AC continues to cycle??
Thread Starter
Racer
Joined: Feb 2012
Posts: 319
Likes: 0
From: Daytona Beach Florida
AC continues to cycle??
Well I was able to braze the crack on the condenser.. Vacuum down for about 40minutes and held..l filled it with 36oz of freon....Ac blows ice cold..26*f at the vents.... But I believe I might havean issue..
The compressor keeps cycling (in automatic mode)even after I raise the temp to 90*F... The air blows hot but the compressor keeps kicking in..is this normal.. Seems the only way to keep the compressor from kicking on it to manually set it to floor vent....
The owners manual says ac will be on when any ac mode is set ...is this regardless of temp set??
Any help wild be appreciated..Thanks in advance..
The compressor keeps cycling (in automatic mode)even after I raise the temp to 90*F... The air blows hot but the compressor keeps kicking in..is this normal.. Seems the only way to keep the compressor from kicking on it to manually set it to floor vent....
The owners manual says ac will be on when any ac mode is set ...is this regardless of temp set??
Any help wild be appreciated..Thanks in advance..
Le Mans Master
Joined: Aug 2005
Posts: 7,392
Likes: 216
From: Merritt Island, FL
With the auto climate control, the compressor will cycle in all settings other than floor vent and face vent. Perfectly normal behavior. Temp setting does not matter, as far as I know, other than to say that if the outside temp is below 40, I do not think the compressor cycles.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Its electronic a/c.....yes, if you have it set to a/c auto then it has to run the compressor to be able to have cold air in the evaporator to blend with heated air to deliver 90* air at the vent.
BTW
90 is default high and 60 is default low so that everything is bypassed and it goes to FULL hot or cold without any blend.
Your evap has hot and cold. Its mixed thru a door that allows some of each to enter. That door is constantly moving to adjust. Interior temp sensor tells the system what to do. A/c comp runs in def and bi as well as auto. Only heat and vent/econ are non compressor settings.
26 at the vents NOW? Must be under 50 ambient. Wait till July or Aug when its a little warmer to see how well it does. R-12 definately does a better job when the ambient goes up.
BTW
90 is default high and 60 is default low so that everything is bypassed and it goes to FULL hot or cold without any blend.
Your evap has hot and cold. Its mixed thru a door that allows some of each to enter. That door is constantly moving to adjust. Interior temp sensor tells the system what to do. A/c comp runs in def and bi as well as auto. Only heat and vent/econ are non compressor settings.
26 at the vents NOW? Must be under 50 ambient. Wait till July or Aug when its a little warmer to see how well it does. R-12 definately does a better job when the ambient goes up.
Last edited by leesvet; Mar 16, 2012 at 10:05 PM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
26 at the vents is impossible.
R12 freezes at 30 psi; R134 at 28 psi. Whatever gas is coursing through the Evaporator is picking up sensible heat after it boils which raises it's temperature but not it's pressure. This is referred to as superheat so at 28 psi, the temperature of the gas is actually six to eight, maybe even 10 degrees higher. If you want to see what it is, put a thermometer on the Evaporator outlet while observing the low pressure gage. Subtract the satuation pressure/temp from your thermometer reading and that will give you the superheat.
The Low Pressure Switch for R12 cuts power to the Compressor at 25 psi; for R134, 22.5 psi. Neither pressure, with superheat, is below freezing and that keeps the Evaporator from becoming a big ice cube (which if it did, nothing - air - would pass through it and you'd get zero out of the vents).
You need to put gages on it and obtain the high and low side pressures. It's either undercharged (assuming it's 70 or better at the Condenser) or the orifice is full of junk, but knowing the low and high side and the temp of the air at the Condenser will tell you if there's a problem.
R12 freezes at 30 psi; R134 at 28 psi. Whatever gas is coursing through the Evaporator is picking up sensible heat after it boils which raises it's temperature but not it's pressure. This is referred to as superheat so at 28 psi, the temperature of the gas is actually six to eight, maybe even 10 degrees higher. If you want to see what it is, put a thermometer on the Evaporator outlet while observing the low pressure gage. Subtract the satuation pressure/temp from your thermometer reading and that will give you the superheat.
The Low Pressure Switch for R12 cuts power to the Compressor at 25 psi; for R134, 22.5 psi. Neither pressure, with superheat, is below freezing and that keeps the Evaporator from becoming a big ice cube (which if it did, nothing - air - would pass through it and you'd get zero out of the vents).
You need to put gages on it and obtain the high and low side pressures. It's either undercharged (assuming it's 70 or better at the Condenser) or the orifice is full of junk, but knowing the low and high side and the temp of the air at the Condenser will tell you if there's a problem.
Thread Starter
Racer
Joined: Feb 2012
Posts: 319
Likes: 0
From: Daytona Beach Florida
26 at the vents is impossible.
R12 freezes at 30 psi; R134 at 28 psi. Whatever gas is coursing through the Evaporator is picking up sensible heat after it boils which raises it's temperature but not it's pressure. This is referred to as superheat so at 28 psi, the temperature of the gas is actually six to eight, maybe even 10 degrees higher. If you want to see what it is, put a thermometer on the Evaporator outlet while observing the low pressure gage. Subtract the satuation pressure/temp from your thermometer reading and that will give you the superheat.
The Low Pressure Switch for R12 cuts power to the Compressor at 25 psi; for R134, 22.5 psi. Neither pressure, with superheat, is below freezing and that keeps the Evaporator from becoming a big ice cube (which if it did, nothing - air - would pass through it and you'd get zero out of the vents).
You need to put gages on it and obtain the high and low side pressures. It's either undercharged (assuming it's 70 or better at the Condenser) or the orifice is full of junk, but knowing the low and high side and the temp of the air at the Condenser will tell you if there's a problem.
R12 freezes at 30 psi; R134 at 28 psi. Whatever gas is coursing through the Evaporator is picking up sensible heat after it boils which raises it's temperature but not it's pressure. This is referred to as superheat so at 28 psi, the temperature of the gas is actually six to eight, maybe even 10 degrees higher. If you want to see what it is, put a thermometer on the Evaporator outlet while observing the low pressure gage. Subtract the satuation pressure/temp from your thermometer reading and that will give you the superheat.
The Low Pressure Switch for R12 cuts power to the Compressor at 25 psi; for R134, 22.5 psi. Neither pressure, with superheat, is below freezing and that keeps the Evaporator from becoming a big ice cube (which if it did, nothing - air - would pass through it and you'd get zero out of the vents).
You need to put gages on it and obtain the high and low side pressures. It's either undercharged (assuming it's 70 or better at the Condenser) or the orifice is full of junk, but knowing the low and high side and the temp of the air at the Condenser will tell you if there's a problem.
Well I took the temp readings with a tube thermometer and a temp gun.. Both registered 26*...
Low pressure side fluctuated between 21 and 42 as the compressor cycled on and off (less than two cycles per minute)..High pressure side i think was around 150-170...ambient air temp was around 52 and it just finished raining.... Does this sound right?
I did notice that the low pressure lines would freeze as soon as the compressor cycled....And I would see a lite mist coming from the vents..
Ac seems to be working fine to me.. My only concern was the operation of the climate control setup...
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
I didn't make up the science.
Specs are 8 cycles or less per minute at 70 degrees, though a fully charged system shouldn't cycle at that temp. At 52, 2 cycles or less would be ok. I'd recheck when it's warmer. Also take pressures with the Main Fan ('89 or lower) - both fans '90 and above - cranking; engine at a steady 1200 t0 1500 rpms; Controls at max, windows down or doors open. Idle pressures don't tell the whole story. Check the Low Pressure Switch threshold by disconnecting the Blower Motor Connector and the lack of air flow will drop the low side. Then note your gage when the compressor cycles off. Some switches are adjustable and have a screw between the terminals. You turn it counterclockwise to lower the threshold; clockwise to raise it. You want 22.5 psi for R134; 25 psi for R12. Try 1/2 turns at a time if it needs adjustment and recheck. If it's not adjustable, buy a new one though every new one I've seen is set for R134 and if you're using R12, make sure it's adjustable so that you can reset it (or it'll ice over).
Specs are 8 cycles or less per minute at 70 degrees, though a fully charged system shouldn't cycle at that temp. At 52, 2 cycles or less would be ok. I'd recheck when it's warmer. Also take pressures with the Main Fan ('89 or lower) - both fans '90 and above - cranking; engine at a steady 1200 t0 1500 rpms; Controls at max, windows down or doors open. Idle pressures don't tell the whole story. Check the Low Pressure Switch threshold by disconnecting the Blower Motor Connector and the lack of air flow will drop the low side. Then note your gage when the compressor cycles off. Some switches are adjustable and have a screw between the terminals. You turn it counterclockwise to lower the threshold; clockwise to raise it. You want 22.5 psi for R134; 25 psi for R12. Try 1/2 turns at a time if it needs adjustment and recheck. If it's not adjustable, buy a new one though every new one I've seen is set for R134 and if you're using R12, make sure it's adjustable so that you can reset it (or it'll ice over).
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Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
^^When mine cycles, If I hook the gauge to the low side......You can watch the pressure drop as the a/c kicks on and it drops so low that the pressure switch kicks off the compressor. Then as the coolant races around the closed loop the pressure increases and the compressor kicks on again.....
I stick another can in and that raises the pressure and it equalizes throughout the system and the cycling stops.
Understand, when I am putting some coolant in, the dials will start to go to the red zone as the compressor is sometimes slower at grabbing the coolant than the can is at filling that area.......so, I'll close the valve a bit to allow less flow from the can to the low side line, but that doesn't mean the system is full.....it just means that the area before the compressor has some high pressures..........as the compressor pushes coolant/gas through the system, the low side readings drop......it takes a while.
Understand, Suncr knows 10x more about these systems, I'm just telling you what I see from my observations.....maybe you get another perspective that may be helpful
I stick another can in and that raises the pressure and it equalizes throughout the system and the cycling stops.
Understand, when I am putting some coolant in, the dials will start to go to the red zone as the compressor is sometimes slower at grabbing the coolant than the can is at filling that area.......so, I'll close the valve a bit to allow less flow from the can to the low side line, but that doesn't mean the system is full.....it just means that the area before the compressor has some high pressures..........as the compressor pushes coolant/gas through the system, the low side readings drop......it takes a while.
Understand, Suncr knows 10x more about these systems, I'm just telling you what I see from my observations.....maybe you get another perspective that may be helpful
Last edited by jhammons01; Mar 17, 2012 at 12:14 PM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Whoa - easy on the gas. It is hard to get everything out of a 12 oz can, but I'd wouldn't exceed the factory fill and if it's converted to R134, aim for only 80% of that. You can easily end up with too much and the high side will be off the charts once it's 90 degrees or better. I know one guy around here was posting a low side of something like 60 psi or more. Well, for R134, that usually gives a vent of 85 degrees and I'd guess the high was pushing 400 which is enough to trip the high limit (or you hope it does before it ends up with a hole in the hood).
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
^^no, what I am saying is.....IF you just fill the it the first time....and you see the gauge go up to the red zone.....some would call it a day and unhook
What I am saying is that when my is cycling like that, and I start to fill, the gauge goes almost to the red and it is scary, but then as the compressor continues to run and suck in the can.....the gauge comes back down well below the green....
It's like filling the radiator, you have to be patient and once the flow has leveled out then you know it is really full.
The a/c res sorta does the same thing....so if you aren't familiar, the first time it goes to the danger level, someone may close the valve and disconnect the hose and gauge.
I'm saying, let it level out before you call it full, you may in fact be a can shy of full......When mine cycles, it seems to take about 80% of a can to get it full again.
again...just an observation.
Plus SunCr, I need your help on my own A/C....the front seal that has been leaking, finally gave in and now a charge leaks out within a day.
I'll start a thread...watch for it.
What I am saying is that when my is cycling like that, and I start to fill, the gauge goes almost to the red and it is scary, but then as the compressor continues to run and suck in the can.....the gauge comes back down well below the green....
It's like filling the radiator, you have to be patient and once the flow has leveled out then you know it is really full.
The a/c res sorta does the same thing....so if you aren't familiar, the first time it goes to the danger level, someone may close the valve and disconnect the hose and gauge.
I'm saying, let it level out before you call it full, you may in fact be a can shy of full......When mine cycles, it seems to take about 80% of a can to get it full again.
again...just an observation.
Plus SunCr, I need your help on my own A/C....the front seal that has been leaking, finally gave in and now a charge leaks out within a day.
I'll start a thread...watch for it.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Red, Blue, Pink and Purple mean nothing. Go to Harbor Freight and buy something with some numbers on it. Get a pressure/temp chart for whatever you're using. Keep in mind where each gas freezes and my 2 cents about superheat. Most mobile systems are designed to squeeze something around 200 psi of liquid through a restriction with a screen in it dropping it to around 25, maybe 32 psi at 70 degrees, compressor at max efficiency which means 1200 to 1800 rpms. Everything will vary according to ambient, but your fan(s) will cycle on/and off to maintain the 200 psi average and it will all fall into place.
