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Old 07-08-2018, 07:11 PM   #10
diveplane
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Join Date: Nov 2016
Location: Tulsa
Posts: 298
Re: a/c symptoms, need help diagnosing issues

i rebuilt my ac on truck complete new parts.

first thing to check is the 2 shut down sensors

one is connected to the evap canister also known as accumulator , if i remember low pressure shut down switch.
other one is located on the ac compressor its self thats the high pressure shut down switch.


try those first u can by pass the low pressure switch by unplugging it and then connect a paper clip bend it to a u shape short the 2 terminals this by passes the low pressure switch circuit, see if ac pump engages, front magnetic fly wheel should spin.

dont run it this way to long just for tests to rule out a faulty low end pressure switch.

also check relays i think one relay behind glove box controls ac compressor power.

any disconnection of ac lines youll need to evap any refrigerant in there first, not good idea to vent this stuff into atmosphere but if u dont have the funds or option pressing on the low end fill and vent valve will discharge any refrigerant, and pressure in lines.

always replace o rings with new ones and dip them in pac ac oil.


other thing after this is to open ac line up at condenser located at front of truck, this is a big job thx to Chevy design as u need to remove front grille first.
think the 98 trucks chevy moved the connections inside engine bay area.

the top connection that slopes downward is the orifice tube, these foul up after number years and start to block coolant flow, replace with a new one if yours is black gummed up.

the orifice converts the refrigerant to a liquid to gas state in ac or its vice versa.

Last edited by diveplane; 07-08-2018 at 07:27 PM.
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