txv in ac where? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

86c20 · 07-10-2013, 08:37 AM

ok guys so i am trying to gett the ac in my k30 going it has never worked before so i am shooting in the dark here. i put some 134 in it as it has been changed over at some point cpmp came on had about 35 on the low side but i noticed that the bottom of the condenser was freezing up to the high pressure port. so i am thinking that the txv is gummed up maybe?? when i got thte truck the owner was dicking with the ac and i dont know what he did at all. and it does not even start to cool off at all. any suggestions?
also if i need to change out the txv what one do i put in? and does anyone konw a part number for the right evap for 134 in these trucks?
thanks guys, mike

hyatt · 07-10-2013, 08:45 AM

not sure what year you are working on but on 80s and 90s truck there is a orrifice valve in hi pressure line of evaporator that if clogs will cause the freeze up you are talking about Remove the line and use needlenose pliers to remove it and replace Flush all lines out while you have it open

86c20 · 07-10-2013, 06:09 PM

ok what should be used as a flush?

hyatt · 07-10-2013, 07:11 PM

There is a comercial flush available but I just used air pressure Did ac work for 23 years I would replace accumulator while you had system open
Posted via Mobile Device

**hatzie** · 07-10-2013, 10:34 PM

Flush it out with a commercial flush. If you get a sludgy mess from the condenser, evaporator, or lines you'll want to re-think how much you need the AC.
Badly done 134 conversions can make a mess of the AC system internally.

86c20 · 07-10-2013, 10:59 PM

i think this one was done ok as i think the comp has been changed to one only for 134
also looking at the orifice tubes what is the deal with them? diff size and one that is variable?? hows this i want as cold as i can get. and the money is not the problem it is just the time to get it there lol. i am going to pump it down and check the line and the ot and see whats going on in there. i am surpised tho that is not leaking yet. as i had some one pump it down to check and they said it had a big leak so idk about that

**hatzie** · 07-12-2013, 10:23 AM

Get the variable valve. It's supposed to make the system more R134 friendly.
If you're really ambitious change out the tube and fin condenser for a high efficiency unit... I believe they are called parallel flow condensers. They make a HUGE difference in cooling and head pressure.

86c20 · 07-14-2013, 11:51 AM

ok so i put in the new orifice fushed it out and charged it up. this is where i stand.
low side. 40-50
high side is at 150 and floats some about 5 pis
and i am geting about a 40* drop across the condenser. dont seem like enough.
out of the pump is in the 175 area and out of the condenser is 140ish little lower.
HELP haha

86c20 · 07-14-2013, 01:45 PM

ok got a correction to make. its 55on the low 140 on the high with 48* outthe vents witch i thought was oddas it was not all that cold. took it for a drive and got an instant 38* out the vents at about 15mph and it got even colder as i drove.

does this seem some what right to you guys?

07-10-2013, 08:37 AM	#1
86c20 Registered User Join Date: Mar 2012 Location: edgartown mass Posts: 852	txv in ac where? ok guys so i am trying to gett the ac in my k30 going it has never worked before so i am shooting in the dark here. i put some 134 in it as it has been changed over at some point cpmp came on had about 35 on the low side but i noticed that the bottom of the condenser was freezing up to the high pressure port. so i am thinking that the txv is gummed up maybe?? when i got thte truck the owner was dicking with the ac and i dont know what he did at all. and it does not even start to cool off at all. any suggestions? also if i need to change out the txv what one do i put in? and does anyone konw a part number for the right evap for 134 in these trucks? thanks guys, mike __________________ 1986 c20 "the hillbilly" 350 sm465 3.42gears 21mpg at 70mph 1985 k30 "the ice cream truck from hell" no rust az truck 197-8??? c30 "ramp truck" 454 1978 monte carlo 350 350th with 2.73 gears. no rust. sc car

07-10-2013, 08:45 AM	#2
hyatt Registered User Join Date: Dec 2012 Location: sparta tennessee Posts: 345	Re: txv in ac where? not sure what year you are working on but on 80s and 90s truck there is a orrifice valve in hi pressure line of evaporator that if clogs will cause the freeze up you are talking about Remove the line and use needlenose pliers to remove it and replace Flush all lines out while you have it open __________________ 1946 car hauler 1948 surburban 1937 chevy sedan 1940 olds sedan (project) 1967 ss396 chevelle 1999 dually crewcab(24000 miles)

07-10-2013, 06:09 PM	#3
86c20 Registered User Join Date: Mar 2012 Location: edgartown mass Posts: 852	Re: txv in ac where? ok what should be used as a flush? __________________ 1986 c20 "the hillbilly" 350 sm465 3.42gears 21mpg at 70mph 1985 k30 "the ice cream truck from hell" no rust az truck 197-8??? c30 "ramp truck" 454 1978 monte carlo 350 350th with 2.73 gears. no rust. sc car

07-10-2013, 07:11 PM	#4
hyatt Registered User Join Date: Dec 2012 Location: sparta tennessee Posts: 345	Re: txv in ac where? There is a comercial flush available but I just used air pressure Did ac work for 23 years I would replace accumulator while you had system open Posted via Mobile Device __________________ 1946 car hauler 1948 surburban 1937 chevy sedan 1940 olds sedan (project) 1967 ss396 chevelle 1999 dually crewcab(24000 miles)

07-10-2013, 10:34 PM	#5
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: txv in ac where? Flush it out with a commercial flush. If you get a sludgy mess from the condenser, evaporator, or lines you'll want to re-think how much you need the AC. Badly done 134 conversions can make a mess of the AC system internally. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-10-2013, 10:59 PM	#6
86c20 Registered User Join Date: Mar 2012 Location: edgartown mass Posts: 852	Re: txv in ac where? i think this one was done ok as i think the comp has been changed to one only for 134 also looking at the orifice tubes what is the deal with them? diff size and one that is variable?? hows this i want as cold as i can get. and the money is not the problem it is just the time to get it there lol. i am going to pump it down and check the line and the ot and see whats going on in there. i am surpised tho that is not leaking yet. as i had some one pump it down to check and they said it had a big leak so idk about that __________________ 1986 c20 "the hillbilly" 350 sm465 3.42gears 21mpg at 70mph 1985 k30 "the ice cream truck from hell" no rust az truck 197-8??? c30 "ramp truck" 454 1978 monte carlo 350 350th with 2.73 gears. no rust. sc car

07-12-2013, 10:23 AM	#7
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: txv in ac where? Get the variable valve. It's supposed to make the system more R134 friendly. If you're really ambitious change out the tube and fin condenser for a high efficiency unit... I believe they are called parallel flow condensers. They make a HUGE difference in cooling and head pressure. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-14-2013, 11:51 AM	#8
86c20 Registered User Join Date: Mar 2012 Location: edgartown mass Posts: 852	Re: txv in ac where? ok so i put in the new orifice fushed it out and charged it up. this is where i stand. low side. 40-50 high side is at 150 and floats some about 5 pis and i am geting about a 40* drop across the condenser. dont seem like enough. out of the pump is in the 175 area and out of the condenser is 140ish little lower. HELP haha __________________ 1986 c20 "the hillbilly" 350 sm465 3.42gears 21mpg at 70mph 1985 k30 "the ice cream truck from hell" no rust az truck 197-8??? c30 "ramp truck" 454 1978 monte carlo 350 350th with 2.73 gears. no rust. sc car

07-14-2013, 01:45 PM	#9
86c20 Registered User Join Date: Mar 2012 Location: edgartown mass Posts: 852	Re: txv in ac where? ok got a correction to make. its 55on the low 140 on the high with 48* outthe vents witch i thought was oddas it was not all that cold. took it for a drive and got an instant 38* out the vents at about 15mph and it got even colder as i drove. does this seem some what right to you guys? __________________ 1986 c20 "the hillbilly" 350 sm465 3.42gears 21mpg at 70mph 1985 k30 "the ice cream truck from hell" no rust az truck 197-8??? c30 "ramp truck" 454 1978 monte carlo 350 350th with 2.73 gears. no rust. sc car



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