AC Pressure Switch Jumpered At The Plug
#1
07-31-2018, 04:16 PM
AC Pressure Switch Jumpered At The Plug
hey folks, this must be my day for surprises. While troubleshooting another problem I found the pressure sensor on the side of the accumulator unplugged and jumpered. Any idea why? Seems like I remember someone telling me once upon a time that when you can’t get the AC compressor to kick in and take Freon that jumping the low pressure sensor would force it on... is that the low pressure sensor? I haven’t started it up yet. Looking to learn more. I have since removed the jumper wire and plugged it back in.
Thoughts?
Thoughts?
#2
07-31-2018, 08:10 PM
Yes, in order to charge the system from empty a jumper can be placed into the plug. I would guess someone forgot after servicing the AC system or the switch is bad and didn't get replaced.
The low pressure switch is usually on the accumulator/drier
Neal
The low pressure switch is usually on the accumulator/drier
Neal
#3
08-01-2018, 05:50 AM
I’ll start it up today and look it over, I checked the Freon with a recharge kit and it is in the green (I know it’s not the most accurate). I did remove the jumper and plugged it back in. Will see. Do you or anyone else. Know where the high pressure sensor is. Also guessing if the sensor was failing that someone could have jumped it to make it work for the time being (to discuss the problem). I’ll know more today.
thanks
thanks
#4
08-01-2018, 06:57 AM
I have not looked for it on my H2 but on my GMC truck (same generation and basically the same as an H2 in many respects) the high pressure switch is down low right next to the edge of the radiator (AC condenser) on the passenger side. Knowing GM it is likely in the same spot on our H2's.
#5
08-02-2018, 05:14 AM
Thanks buddy! I’ll take a peek today. I did start it up and with the low pressure sensor plugged in the ac compressor will not kick in. So it could be a bad switch or be low on Freon. I don’t suspect Freon because I have a recharge can and it shows it in the green (but they are not the most accurate gauges). Might make sense to rent some real gauges to rule out pressure loss. If it is good on pressure I guess I need to replace the low pressure switch since I know it was working when it had the jumper in it.
#6
08-02-2018, 09:07 AM
If it works with the jumper in then the charge is good. If it was mine I'd replace the pressure switch and call it good
The switch is easy to change, the service port its screwed onto should have a shrader valve so when the switch is removed you should loose no freon.
Its as easy as removing the old one and screwing the new one on the service port
I've replaced a few that had leaking ports, turn the system on and let it cool off for a few minutes, then change the switch with the system running as the pressure will be around 30 psi which will reduce the amount of freon lost. You can actually hold it with your finger while preparing to install the new switch.
Neal
The switch is easy to change, the service port its screwed onto should have a shrader valve so when the switch is removed you should loose no freon.
Its as easy as removing the old one and screwing the new one on the service port
I've replaced a few that had leaking ports, turn the system on and let it cool off for a few minutes, then change the switch with the system running as the pressure will be around 30 psi which will reduce the amount of freon lost. You can actually hold it with your finger while preparing to install the new switch.
Neal
Last edited by legerwn; 08-02-2018 at 09:10 AM.
taking it to be serviced Monday morning.
#10
08-06-2018, 04:51 PM
Having completely re-built and re-gassed my system it sounds like you may have a leak.
The switch on the accumulator dryer is used to detect that the system has enough pressure to operate.
You could check the compressor-clutch engages when you activate the "Snow Flake" button on your A/C, if the A/C comes-on then goes-off shortly afterwards then either the compressor hasn't engaged or the pressure is too low.
To be accurate the refridgerant it isnt Freon but R134a of which the H2 requires exactly 1.6lbs. Your service depot should extract all the old R134a and test your system by checking it can hold a vacuum for at least an hour (otherwise its pointless re-charging it)
They should add the required amount of refridgerant and replace any lost PAG Oil to prevent your compressor siezing, they may also add some UV dye to assist tracing any slow leaks.
The are some excellent articles on A/C systems by ChrisFix on youtube.
The switch on the accumulator dryer is used to detect that the system has enough pressure to operate.
You could check the compressor-clutch engages when you activate the "Snow Flake" button on your A/C, if the A/C comes-on then goes-off shortly afterwards then either the compressor hasn't engaged or the pressure is too low.
To be accurate the refridgerant it isnt Freon but R134a of which the H2 requires exactly 1.6lbs. Your service depot should extract all the old R134a and test your system by checking it can hold a vacuum for at least an hour (otherwise its pointless re-charging it)
They should add the required amount of refridgerant and replace any lost PAG Oil to prevent your compressor siezing, they may also add some UV dye to assist tracing any slow leaks.
The are some excellent articles on A/C systems by ChrisFix on youtube.