heater won't stay hot?

2002 CHEVROLET S-10
78,000 MILES • 6 CYL • 4WD • AUTOMATIC
Avatar
MMCK1313
  • MEMBER
  • 1 POST
I have a 2002 chevy s-10 zr-2. I have a problem with my heater that is driving me crazy. I have changed the thermostat and flushed my cooling system. When I first start it, it seems the heater is working fine. the air is very hot. After it comes up to running temp, the heat slowly turns cold. The selector for my vents is not working correctly. It will not switch between face and feet etc. The water going in is hot, the return is cold. Has anyone heard this problem before? I am at my end and need help.
Dec 16, 2007 at 8:02 AM
Advertisement
Avatar
RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
The water going in is hot, the return is cold.

Look for a heater control valve-check for clogging heater hose/s and heater core.
Dec 16, 2007 at 8:20 AM
Avatar
STRAILER
  • ✓Experienced Mechanic
  • 55,649 POSTS
It sounds like you have two problems, the first is the heater core is clogged I would use a garden hose to help flush it out, next I would make sure the vacuum source under the hood that goes to the fire way and the HVAC system is not broken. Please go over this video it will help;

https://www.youtube.com/watch?v=SNRb6pSwYuU&t

Please go over this guide as well for the broken vacuum line.

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

Please go over these guides and get back to us.
Nov 22, 2024 at 7:20 AM
🔧 Tools & Auto Repair Parts
Find automotive tools, diagnostic equipment, and replacement parts for your next repair.
Shop on Amazon →
Paid affiliate link. As an Amazon Associate, we earn from qualifying purchases.
Add a reply
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.

Ask a new question

Frequently Asked Problems for This Vehicle