Electrical Issues with Heater & AC

This weekend I was working on a Friends Suburban and before we put in the stereo the Heater and AC Seemed to work fine.

Now while installing the stereo we used a wiring harness. I hooked up the Illumination wires from the stereo to the illumination wires listed on the harness and it blew the Power Door Lock Fuse. After replacing the fuse the power locks work again.

But now when we turn on the Heater and AC the AC lights and Defrost Lights no longer Light up. The blower works fine but we are not getting any heat. Is this something that could have been caused from the stereo wiring?

Any ideas where to start looking. We have checked all of the fuses and wiring looks okay. Checked Coolany levels and all seems to be fine.

Is the new harness still connected? Disconnect it immediately. You have shorted something out, that's what blew the fuse. Shorts can cause fires. You need to go back to square one to begin with. Remove what you did (connection wise). Fix what's not working, and then map out this harness before you connect it. The harness could be bad or have some internal connections or cross over you're not aware of.

already rewired it. everything works except no heatfrom the heater. The blower works just no heat.

The only thing that caused a problem was the illumination wire. Both were labled illumination, the wire on the harness and wire on the stereo. but when we tried it, the fuse blew.

the fuse did its job. I disconnected the illumination wires, replaced the fuse and we still have no heat. every thing seems to work fine.

now while we were working on it out side , the temurature dropped to about 20 F, this was the first cold day of the year. My thinking is tht he has a bad thermostat, possibly a heater core. does anyone know if there are any other electrical connection for the heating system. All fuses check good.

I am just trying to eliminate the stereo from the problem. I have never had a problem with a heter caused by a stereo installation. Just a bad coincedence ?

the flow of hot water from the engine to the htr core is not electrical in nature. You need to figure out if hot water is getting to the core. If yes, then are the dampers working, this would be your electrical issue.

The guy i was working with took it in to the shop and it's a blown Heater core gasket. wasn't anything electrical