1996 chevy 1500 van with gladiator conversion.
Two separate issues:
First the speedo reads higher than it should. I do know that the van was in the shop before my purchase and they put in a junkyard ecu from a truck. Might that have thrown off what the speedo reads thinking it has a truck gear ratio? Is there a way to reset that to the correct setting?
The rear A/C blows hot. There is no rear temperature control, only fan speed. When I got the van, the A/C was marginal and a recharge made it ice cold, and has appeared to hold it's charge for the last month of so. However, I only get hot air from the rear system. Unsure how the system works, I'm guessing there is a blender door or something. Or is it possible the rear a/c system can have it's own leak, without causing a problem for the front? Clueless how a system like that works, so I have no idea what to diagnose, and don't want to rip stuff apart until I have some idea how things work.
is a heater core involved with the AC system in any way? (general question)
Once I blew a coolant leak on my 1994 chevy van after some wintertime snow hoonage and getting it stuck a few times and it was overheating, shop diagnosed it as a leaking "rear heater core", they just bypassed it with some hose to fix the leak and saved me a bunch of money, since I did not have a rear heater/AC system.
not sure on a van but on the 90 suburban the rear ac hoses came right off the front system and if you got a leak in those and wanted to bypass you needed to install hoses for a truck with no rear air, i'd see if there are even hoses hooked to the rear.
the speedo problem is in the computer. it thinks you have whatever gear the truck had, so your speedo is off. the right way to fix it is to have the pcm reprogrammed to your gear ratio and tire height. however you might be able to fix with resistors if you know how to do that sort of thing. i bet google would turn up someone who has done it.
I got the van on ramps to have a better look at the AC system. Definitely some missing parts. Really need a diagram of everything to know for sure.
There is a hose that comes from the rear, that appears broken, leading to a circular bracket that must of had some canister(canister is missing). A second hose that went to the canister also has a broken end runs off towards the front of the van. All on the driver side. Looks like the lines go to the passenger side, then up to the engine bay. In the engine bay there is a small hard line that is covered with duct tape. No apparent place for that line to tie into the AC system.
I'm guessing it must be blocked off somehow, as I can't imagine it holding a charge with these parts broken/absent.
I had a 97 I converted from front and rear to just front. In order to replace the lines, a ton of interior had to be removed, it was easier to just replace a couple of lines in front
