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Will the AC compressor kick in if it is low on Freon? 1994 K3500

J

jrsavoie

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On the 1994 K3500, Will the AC compressor clutch kick in if it is low on Freon?

The 1994 has the Freon converted.

If I jumper the wires off the pressure switch the compressor will kick in. Could be the switch also.

Can I check the Freon level with one of the cheap cans with a gauge from a parts store?
 
Im not the expert.

Comp will not kick on once the pressure is to low. When charging an empty system you have to jumper the swicth til PSI is high enough.
You can't check level of freon only the PSI. To know for sure you have to empty the system then weigh the freon and put in the correct amount.
Anything else is a guess.
 
That LP switch on the dryer is one of the weaknesses.
It will act erratically.

You may just want to change it and see if it fixes the problem.
 
You need a manifold for both high and low pressure to check the system for proper refrigerant amount. The compressor is in survival mode by not turning on. The refrigerant also contains the lubricant for it. Low refrigerant means low lubrication.

Make sure you have the plastic caps on both "schrader" valves. They are more than a dust cover, they also help seal the system so it doesn't leak.
 
JMJNet said:
That LP switch on the dryer is one of the weaknesses.
It will act erratically.

You may just want to change it and see if it fixes the problem.
Click to expand...
That was one of the problems I had with my a/c. You can buy a new switch and swap it our yourself. That won't shoot freon everywhere. A/C leaks are common . Most cars need a recharge every 10 years or so.
 
You need gauges. If you jump the switch the compressor will run even if it is empty. I was in SC about 3 weeks ago when my A/C quite. Found a parts store and replaced the low pressure switch and A/C works like a dream. To awnser your question. If the freon is low will the compressor clutch kick in. Yes it will, but will be erratic and cycle very quickly.
 
Ambient air temps. Seems like occasionally it will give cool air for a while

The clutch has not kicked in, while I was watching. It seemed like it may have kicked in while going down the road though
 
jrsavoie said:
Do you have detailed instructions on changing the switch? Tips or tricks?
Click to expand...

Sounds like your cycle switch. It is cheap and I would try this first. 15mm wrench and 5 minutes is all you need.
1- Unplug the switch on the side of the receiver drye
2- Take the 15mm wrench and turn the low pressure switch off
3- A new o-ring usually comes with the switch, Replace the oring.
4- Install the new switch.
5- Plug the switch back in.

You will lose some freon when replacing the switch, be quick to turn the switch off and turn it on. This will make sure for minimum freon loss. Also be prepared with a tire stem core tool. If you hear hissing try to tighten the schrader valve to stop the leaking. If you cant get it to stop leaking you can try to put the new sensor on but the o ring my not seat properly.
 
It's always a good idea to put a little bit of PAG or mineral oil on the o-ring if you replace it, but it isn't neccesary. The low pressure switches in our trucks fail ALOT because GM in there infinite wisdom ran all of the current for the clutch through the low pressure switch and uses it to power the clutch directly. Every other manufacturer out there used the switch to turn the relay on and off to power the clutch, but not GM. They use the relay to send power to the switch that then sends the power to the clutch. So your switching about 2 amps of current and arcing the points in the switch everytime it cycles on and off.
 
Hasn't somebody come up with a relay triggered by the switch yet? Doesn't sound that hard to wire in.

THEFERMANATOR said:
It's always a good idea to put a little bit of PAG or mineral oil on the o-ring if you replace it, but it isn't neccesary. The low pressure switches in our trucks fail ALOT because GM in there infinite wisdom ran all of the current for the clutch through the low pressure switch and uses it to power the clutch directly. Every other manufacturer out there used the switch to turn the relay on and off to power the clutch, but not GM. They use the relay to send power to the switch that then sends the power to the clutch. So your switching about 2 amps of current and arcing the points in the switch everytime it cycles on and off.
Click to expand...
 
THEFERMANATOR said:
It's always a good idea to put a little bit of PAG or mineral oil on the o-ring if you replace it, but it isn't neccesary. The low pressure switches in our trucks fail ALOT because GM in there infinite wisdom ran all of the current for the clutch through the low pressure switch and uses it to power the clutch directly. Every other manufacturer out there used the switch to turn the relay on and off to power the clutch, but not GM. They use the relay to send power to the switch that then sends the power to the clutch. So your switching about 2 amps of current and arcing the points in the switch everytime it cycles on and off.
Click to expand...

Agree 100%.
Depending on what you have for freon. R134a get PAG and r12 gets mineral oil. Do not mix the two. It can ruin the system over time.
 
Diesel Nut said:
Agree 100%.
Depending on what you have for freon. R134a get PAG and r12 gets mineral oil. Do not mix the two. It can ruin the system over time.
Click to expand...

Technically if you have "FREON" it is mineral oil as "FREON" was the trademark name for DUPONT'S origanal refrigerants they came out with, R-12 and R-22. R-134A is technically not freon, but a refrigerant. Most people just call all of them freon since it is easier to say than refrigerant. And for O-rings even in a system using R-134A, it is normally reccomeneded to use mineral oil for O-ring lubrication since PAG is a corroding agent. In the tiny amounts like used on an o-ring, it will have no effect on the system.
 
I have changed that switch a few times, at least, this switch installed on top of a valve so the refrigerant will not spray out (may be a little as long as you pull it out fast).

Don't try it with other cars, though.
 
Is there any particular brand of switch to buy or stay away from?

Being an electrical part, my first thought would be AC Delco.

A part number for ordering?

Thanks for the advice.
 
http://www.rockauto.com/catalog/x,carcode,1053335,parttype,4656

1994 CHEVROLET K3500 PICKUP 6.5L V8 DIESEL Turbocharged : Electrical-Switch & Relay : Refrigerant Pressure Switch Subscribe to RSS feed to be notified when new parts are added for this car View Advice Price Add to Cart
ACDELCO Part # 152844 More Info {#02724750, 06556408, 15253, 2724750} Professional
A/C High Pressure Cut-Out Switch Retainer Ring

$1.95
GPD Part # 1711334 More Info
Blue; Comp Switch High Press; 2-Term

$9.22
GPD Part # 1711425 More Info
High Pressure Cutout

$14.14
FOUR SEASONS Part # 35972 More Info Pressure Switch
Compressor Mounted; 2 Term; Purple

$17.50
FOUR SEASONS Part # 35973 More Info Pressure Switch
Low Pressure Compressor Mounted Cut-Out Switch; 2 Term; Blue or Green

$19.71
ACDELCO Part # 152874 More Info {#15966454} GM Original Equipment One of our most popular parts
HOUSING IS DARK GREEN

$20.79
FOUR SEASONS Part # 35974 More Info Pressure Switch One of our most popular parts
Compressor Mounted Cut-Out Switch; 2 Term; Blue, White or Red

$21.79
FOUR SEASONS Part # 35970 More Info Pressure Switch
Low Pressure Compressor Mounted Cut-Out Switch; 2 Term; Black or Yellow

$24.79
FOUR SEASONS Part # 36655 More Info Pressure Switch
A/C System Mounted Cut-Out Switch; Use only if SW is mounted at Compressor or Condenser

$25.79
FOUR SEASONS Part # 35756 More Info Pressure Switch
Low Pressure Compressor Mounted Cut-Out Switch; 1 Term White

$26.79
FOUR SEASONS Part # 35961 More Info Pressure Switch
Compressor Mounted Cut-Out Switch; 1 Term; Red

$27.79
ACDELCO Part # 1550812 More Info {#02724727, 152830, 89019183} GM Original Equipment One of our most popular parts
A/C High Pressure Cut-Out Switch

$29.79
FOUR SEASONS Part # 35967 More Info Pressure Switch
Compressor Mounted; 1 Term; Green (Only 1 Remaining)
* Stocked in outlying warehouse--shipping delayed up to 1 business day

$29.89
STANDARD MOTOR PRODUCTS Part # PCS140 More Info
Low Pressure Cut-Out

$33.99
FOUR SEASONS Part # 35969 More Info Pressure Switch
Compressor Mounted; 2 Term; Gray
 
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