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2003 mercedes SL 500 no heat just cold air / climate control
Hi there I have a Mercedes SL 500 and I was wondering if you could help me to reset the climate control unit for one I have no heat it blows air just fine I’ve checked all the fuses it doesn't seem to be the fuses
The most common "no heat" issue is the Heater Control valve solenoid (p/no A2308300084) seizes shut, not allowing coolant to reach the heater core. It's located beneath the windshield wiper cowl at the firewall.Instructions for Replacement
the problem was the heat control valve but those instructions are as good as a s*** that guy is a moron
you don't have to remove wipers or motor assembly, cover pins trims what the .................... LOL
for those who are going to do this :
only remove the aluminum barrier BEHIND the engine it will give you access to the area
heat control valve is located ON THE PASSENGER SIDE you would need to remove your starter battery and duct bucket or whatever it is but it's not hard to do at all
the problem was the heat control valve but those instructions are as good as a s*** that guy is a moron
you don't have to remove wipers or motor assembly, cover pins trims what the .................... LOL
for those who are going to do this :
only remove the aluminum barrier BEHIND the engine it will give you access to the area
heat control valve is located ON THE PASSENGER SIDE you would need to remove your starter battery and duct bucket or whatever it is but it's not hard to do at all
I hadn't gotten around to sorting out my heater control valve until today, and after getting into it, I can see how some of the linked instuctions could be considered overkill. For those who need to fix their no heat issue in the future, I'll take time to detail a definitive guide:
1: Raise hood and remove Starter battery.
2. Remove the vent cover to the cabin air filter housing between the starter battery and the windshield (It's held on by 2 squeeze clips on left & right) & Unplug electrical connector.
3. Remove weather strip atop the plastic cowl in front of the windshield and the firewall.
4. Remove 3 retaining bolts holding the wiper arms to the wiper motor (no need to remove wiper motor). If they've never been removed, built up crud will make it seem that adhesive is holding the arms on, but fret not, you'll just need to lever beneath the arms and apply sufficient pressure until they release. Then simply lift the wiper arms off their bolts.
5. Remove the plastic cowl at the base of the windshield by lifting upwards. It's compression fitted, so no hardware to remove.
6. Remove the cabin air filter housing There are 2 metal clips across the topside that just need to be pressed upwards until they release. The housing is then removed by jiggling it whilst pulling upwards. It requires a bit of wiggling to get it to cooperate.
7. Now you'd clearly see the heater control valve sightly left of center (Toward passenger side in North American Models). Unplug the electrical connector. There are a total of 4 hoses with compression retaining clips. Use a pair of pliers to remove each retaining clip up the hose and jiggle each hose off the heater control valve. Due to age and constant heat cycling, there is a good chance that the nipples on the heater control valves are brittle and might break off when trying to remove. If this occurs, don't forget to use a screwdriver to clean out any remaining debris inside the hose(s).
8. Reassemble is the reverse of removal. In the event that you don't have the new heater control valve handy, the hoses can be connected as follows to achieve heat whilst you await delivery of new heater control valve.
a. You can connect the hose from the bottom of the heater control valve that's pointed in an upwards direction, to the lower of the 2 hoses on the firewall. This will route coolant to your heater core. The upper hose on the firewall can be connected to the remaining return hose that travels beneath the battery. Connecting hoses in this manner will allow you to have heat whilst you await installation of the new heater control valve. I'd suggest temporarily reinstalling the starter battery and starting the car at this juncture so you can check that there are no leaks. Run the vehicle to operating temperature with the heater running, check for leaks, then check that heat is circulating in the cabin.
9. Properly stow you jacket and gloves and welcome back to the creature comfort of a heated driving experience once again!
Last edited by Aussiesuede; Oct 11, 2022 at 08:22 PM.
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