94 suburban rear heat questions

Lowstature

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I’m the proud new owner of a 94 suburban.

She has vents in the roof but the controls say rear AC. There is definitely no heat coming out of them but I read people saying theirs blow heat too but don’t have their year listed. Is this truly AC only?

Also looking at replacing carpet and they have 2 choices: with or without vents. I see no vents which makes me wonder more about the roof vents providing heat… is it possible the factory design has no heat past the driver but 3 rows of seating?

Am I missing something?
 
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If you lie down behind the passenger's side rear wheel and look up into the body cavity above, you will see the underside of the floor pan. In the area between the frame / leaf spring and outside fender is where the plumbing lies for the rear heating (hot engine coolant) and cooling (refrigerant); those lines travel from the engine compartment to the rear of the vehicle, along the right side of the body and up into the rear passenger compartment (through the floor pan).

If you see four lines in/out, you have both heat and AC.

If you see two lines or none, then clearly you only one (heat or AC) or neither.

See the attached pictures showing the plumbing, four lines, on my 1998 Suburban w/ heat and air. The first picture is recent (today), the other from a few years ago right after I replaced both AC lines as well as all the rubber hoses in the coolant lines.
 

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someotherguy

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Look at your heater core hose connections at the firewall. An SUV (whether Suburban or Blazer/Tahoe Jimmy/Yukon) with rear heat will have an absolute jumble of connectors there along with a control valve to run an extra pair of hoses to the rear heater core. If you've got that.. SUV has rear heat. If not.. well.. not equipped.

Of course, the rear controls would have a hot/cold temperature selector knob if rear heat equipped.

Richard
 

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That was super helpful, love this site! Thanks guys… turns out no heat in the back…. Stupid to design for 3 rows of seating but at least now I know nothing is broken.

Thanks again
 

someotherguy

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That was super helpful, love this site! Thanks guys… turns out no heat in the back…. Stupid to design for 3 rows of seating but at least now I know nothing is broken.

Thanks again
Stuff people didn't want to pay for in 1994. I had a 1994 Suburban and IIRC it had rear A/C but no rear heat.. it's been a while and a few Suburbans since, though. Things were still often "optional" at that point. It was otherwise a well-equipped truck with the power mirrors, rear door speakers (optional 6 speaker system), etc. but thankfully cloth seats instead of the leather that seems to die early.

Richard
 
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