sirplatypus

Hi,
My car is a 2000 E320 4Matic Wagon with 225k miles on it. I'm currently using it in South Florida where the cabin heating would never be an issue, but will be driving it throughout the next year in New Hampshire. My AC blows well, although it's a bit warm because I ran out of freon a few ounces before the system was completely full. My heat works, but only out of some of the vents and it doesn't get very hot. The middle two dash vents do not blow any hot air, and the driver side foot well also only blows cold air. My driver side vent has fairly weak airflow, only the defrosters will blow heat at full strength. Even then, the air is warm but doesn't get very hot, and if it's cold enough (under 10 degrees F) it'll get almost completely overwhelmed. Since there's several issues here, I'm having trouble really separating what causes each part of the problem. What should I be looking for when I go to fix the heat? I also have yet to test the rest button.

davmil2002

Don't know if you're already familiar with New Hampshire, but take it from an old Vermonter - you've got 5 months to get the heat/air control debugged until at least the point where the defrost can be engaged hot & on the windshield, or you have a problem on your hands. Living with weak air conditioning is one thing, but you've got to be able to thaw that windshield or it will be fogged&/or frozen all the time. What happens is snow gets on your shoes, it melts in the car, humidity goes up, then you park and it turns -20 and you're scraping the windows on the inside.The rest of the time it rains a lot<G>. I love New England, but it's a hard place on cars.

sirplatypus

Yeah I’ve been through it a couple of times already. Defrosters blow nice and strong and generally heat up enough to do their job, and if it’s above 30 make it pretty toasty too. I’m more concerned about the rest of the vents and generally strengthening the heat, and hopefully this is the last winter the car has to go through. The lack of footwell heating is particularly brutal to me as well.

davmil2002

I've never been impressed by the HVAC in our models. In Atlanta it's never as cold as i want the AC. Certainly modern Japanese Air conditioners are tons colder. Luckily it doesn't really get v cold because the heat seems anemic too. Maybe it's just age combined with the complexity has clogged the efficiency of the service

bbirdwell

Check the hard plastic vacuum line that controls the flapper valves. If it is broken just cut out the bad parts and splice it together with a piece of vacuum tubing. You will find the connector in question in the back left under the hood next to the duo valve as you are standing in front of the car and looking at the engine. It is also possible your duo valve is malfunctioning. If so there are DIYs on the forum that explain how to rebuild the duo valve if you don't wish to replace it.

sirplatypus

Funnily enough I recharged the ac for the first time in years and it's been holding up absolutely wonderfully in the south florida summer heat, well beyond my expectations. The rear vents all blow very weakly though, not something I really care to bother tracking down.

sirplatypus

I'm assuming this relates to the lack of heat out of my center vents and floor vents, not the ability of the air to warm up. I'll take a look this week as I'm throwing in new lights and all that I suppose. Would the lack of strong heat also relate to this valve or is that probably just a bad heater core?

Plutoe

I would suggest that you check your or a manual, as I suspect that your hot air vent flow expectations may not be met because of the design of the system. On the other hand you also may have flap issues which can be diagnosed by the flap test outlined th the stickys.