ANY AUTOMOTIVE AC EXPERTS OUT THERE? I'VE GOT PROBLEMS..........

CFD244

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Hi Folks

Spoiler Alert........This is a Toyota Camry:mob:

After coming home from holidays, I have found that the AC clutch on my Camry stays on all the time. I initially figured that it was the pressure switch, so I went ahead and ordered one. When I went to have the system evacuated so I could change the switch, I found that there was only 5 oz's of refrigerant and it's supposed to have 28. At any rate, I figured that since I already had the new switch, I would put it in. Now, even with no refrigerant (clutch relay removed) the electric fans come on and stay on with the ignition switch. When I sub in the old switch, the fans do not come on until the engine temp goes up (this is how it should be).

So I figure that the new switch is defective, as the fans should not be coming on with a cold engine, and no A/C.

My question is.......Will the low refrigerant level cause the compressor to basically cycle on until it fries, or is there a low pressure cut-off aspect of the switch to save the compressor in this type of a situation? I am trying to figure out if I have 2 defective switches, or if I should just put in the old switch, refill and test for leaks.

Thanks FABO
 

jimjimjimmy

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if it's that low you have a leak for sure and yes a low system will cycle the clutch on and off . check the hoses and fittings for leaks this is common spots for leaks a uv light works good since it will most likely have some dye in it .
 

CFD244

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if it's that low you have a leak for sure and yes a low system will cycle the clutch on and off . check the hoses and fittings for leaks this is common spots for leaks a uv light works good since it will most likely have some dye in it .
The clutch was cycling on, and staying on. Trying to figure out if a low system would cause this, or do I have a bad pressure switch.
 

George Jets

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Low freon kicks out the clutch as a safety precaution.

So it is pumping freon, it uses up all the reserve in the system (because it's low) so it kicks the clutch out.

Then the system cycles the used freon through the rest of the system and then the clutch comes back on again. Rinse Repeat, on and on.

You can jumper the clutch with a jump wire and put in the proper Ounces of freon. Then the system will be full and it will quit jumping in and out.

That is until it leaks out out again from where ever it is leaking.

Most folks can get by with a recharge once a year to keep the used systems going. You know, like a tire that loses a little pressure after sitting over the Winter.
 

Charrlie_S

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It's a 1999 Toyota Camry with a 2.2l engine. I think the switch may be referred to as a Trinary switch.
I would have to look up that particular vehicle, but in general a trinary switch performs 3 functions.
1) shuts off the compressor if the refrigerant charge (pressure) is excessively low.
2) shuts off the compressor if the system pressure is too high
3) turns on the cooling fans when the system high pressure reaches a certain level.
How many wires are in the connector for the switch?
I have been retired for some years, so don't have a lot of the manuals on the newer vehicles at home.
Here is a like to the wireing diagram.
All Wiring Diagrams for Toyota Camry CE 1999 – Wiring diagrams for cars
 
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CFD244

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I would have to look up that particular vehicle, but in general a trinary switch performs 3 functions.
1)sor if the refrigerant charge (pressure) is excessively low.
2) shuts off the compressor if the system pressure is too high
3) turns on the cooling fans when the system high pressure reaches a certain level.
How many wires are in the connector for the switch?
I have been retired for some years, so don't have a lot of the manuals on the newer vehicles at home.
Here is a like to the wireing diagram.
All Wiring Diagrams for Toyota Camry CE 1999 – Wiring diagrams for cars
There are 4 wires on the switch. One circuit appears to operate the clutch, and the other pair appear to operate the fan. With 5 oz in a 28 oz system, the clutch kicks in and runs the compressor steady. When I put in a new switch in anticipation for a recharge, the fans cam on as soon as I turned on the ignition and stayed on. I assume that new switch is faulty as I wouldn't expect the fans to kick in right away as that never happened with the old switch.

I am worried about putting in the old switch prior to the recharge in case that was abnormal for the compressor to run steady and the re-charge doesn't solve the issue. It's costing $$$ to have the system evacuated and recharged each time......Hoping to get it right.

Would 5 oz in a 28oz system constitute: "Shuts off the compressor if the refrigerant charge (pressure) is excessively low"?
 

George Jets

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Evacuate it down, put two 12 oz. cans in the system from the "Low" pressure side only. Close the freon manifold valves, roll the compressor over by hand to make sure the AC pump is not hydraulic locked. Then start it up and finish installing the last 4 oz. of R 134 freon by opening the low pressure side manifold valve.

Put a meat thermometer in the interior vents with the AC full on, when the cool temp gets to 60° you know you are getting close ro full.

Keep adding the final freon til the temp out the vent gets to 50° F. Then you are full.

On a cool day you can submerge the frosty freon can into an ice cream pail of hot water, this helps to empty the can an push it into the system.

1 can 12 oz
1/2 can 6 oz.
1/4 can 3 oz.

24 oz + 3 oz = 27 oz.
Think you can figure it out if you dont have a scale, and go by the thermometer.

th-2389590666.jpg
 

CFD244

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I would have to look up that particular vehicle, but in general a trinary switch performs 3 functions.
1) shuts off the compressor if the refrigerant charge (pressure) is excessively low.
2) shuts off the compressor if the system pressure is too high
3) turns on the cooling fans when the system high pressure reaches a certain level.
How many wires are in the connector for the switch?
I have been retired for some years, so don't have a lot of the manuals on the newer vehicles at home.
Here is a like to the wireing diagram.
All Wiring Diagrams for Toyota Camry CE 1999 – Wiring diagrams for cars
Great diagram, but I cannot follow it. LOL.....Too many relays! Can't figure out why the engine and ac fans both run full speed even with the connector removed from the pressure switch.

Would 5 oz in a 28oz system constitute: "Shuts off the compressor if the refrigerant charge (pressure) is excessively low"?
 

Charrlie_S

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Great diagram, but I cannot follow it. LOL.....Too many relays! Can't figure out why the engine and ac fans both run full speed even with the connector removed from the pressure switch.

Would 5 oz in a 28oz system constitute: "Shuts off the compressor if the refrigerant charge (pressure) is excessively low"?
With out digging deeper, and I really don't have time for that, some vehicles have a "fail safe" mode. If the computer sees, values from switches/sensors that don't make sense, it will turn the fans on.
Question: is there a shraeder valve in the port for the switch? If there is, then no need to discharge the system when changing the switch.
 

oldkimmer

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Troy, with only 5 oz in the system the compressor will not cycle as the system pressure is too low. With the key off can u see that the clutch is disengaged? With the key on and engine off what does the clutch do? Is it engaged or not? Does it only engage as soon as u start the car? Kim
 

CFD244

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Troy, with only 5 oz in the system the compressor will not cycle as the system pressure is too low. With the key off can u see that the clutch is disengaged? With the key on and engine off what does the clutch do? Is it engaged or not? Does it only engage as soon as u start the car? Kim
I never thought to check it with the engine and key off. However, I did put the old switch back in with the system totally empty, and the compressor does not come on with the ac activated as it did when there was 5 oz in the system. The new switch that I tried, caused that fans to run full with the key switch turned on. and the engine cold. I assume this new switch is faulty.
 
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