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high pressure cut out switch is jumped..high side..low side

 
wayne's Avatar
  • Answered by:wayne
  • Journeyman
  • Positive Feedback: 96.1 %
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Customer Question

I have an 08 hino 250 that the A/C system does not work. The system will activate if the high pressure cut out switch is jumped. The high side pressure shoots up as soon as the system is turned on with no change in the low side pressures. The refrigerant charge level was verified and correct. There were burnt wire connections found at the A/C switch. I am looking for a blockage in the system and would like to know if the expansion valve is serviceable and how to access it.

 

Optional Information:
Make: Hino
Model: 250
Year: 2008

Submitted: 329 days ago.
Category: Heavy Equipment
Value: $58
Status: CLOSED
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Expert:  wayne replied329 days ago.

Hi I'm Wayne,
I will help you with this,
Good Morning

Was the system open at any time, before this happened,
or this just start all of a sudden
how long does it run before High side pressure goes up and how high is it

Customer replied329 days ago.

The system has had a new compressor installed recently. The system will not turn on unless the high pressure switch is jumped. The pressure climbs to over 500 psi as soon as the compressor comes on with no change in the low side pressure. The A/C stopped working while the truck was out of state and it was change on the road. The system never worked from that point.

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Expert:  wayne replied329 days ago.

Hi
Thank you for that
running a truck shop many years , road service,
cause more problems then it is worth
My Suggestion to you is start over
recover freon, replace drier , evacuate to 300 microns, or 2- 2 1/2 hours , boil all the moisture out , recharge
You have air in system , with out a doubt,
That is why Hi side jumps, and low side empty , air does not compress
Worked on TK, Carrier and A/C systems 34+ years

Customer replied329 days ago.

I have already done this. The fact that the low pressure dose not move leads me to think that there might be a blockage. This is an expansion valve system. I was looking for information on how to access the valve and check it for operation.

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Expert:  wayne replied329 days ago.

Hi
Please don't leave feed back till we are done,
You just gave me a Neg. that goes against me, I am Trying to help you
The system just started this new feed back during questions, and many experts are getting Neg. because of it

OK, Back to your question, I did not know you Performed these things , was never mentioned, So you replaced the drier and evacuated to 300 microns, after it came back from road
Expansion vale is under the dash , in the heater box, with the probe in the evaporator
to test , stick the probe in a ice bath, for 2-3 min and you should be able to blow thru the fitting opening

Customer replied328 days and 22 hours ago.

Sorry about that. The rating thing is a bit confusing. After all we are truck mechanics. The smiley face looks confused thats why I picked it. I will check the expansion vale and get back to you. Again, sorry for any problems I have caused you.

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Expert:  wayne replied328 days and 21 hours ago.

Hi
you did not cause any problems,
Just don't care for this new system, of grading during answering


Yes keep me in touch

Wayne

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Expert:  wayne replied322 days and 15 hours ago.

how did this work out for you

 
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