Update: Both heater core hoses hot. still poor heat.

"Niquemarshall" (dominiquemarshall)
11/16/2014 at 00:08 • Filed to: None

Im out of ideas beside heater control valve. Its vacuum operated

1992 190e

DISCUSSION (9)

Denver Is Stuck In The 90s > Niquemarshall
11/16/2014 at 00:14

Vacuum Leak?

Niquemarshall > Denver Is Stuck In The 90s
11/16/2014 at 00:15

Where do i start?

Denver Is Stuck In The 90s > Niquemarshall
11/16/2014 at 00:16

I'd say replace anything vacuum operated, its easier than looking at everything to find a leak

gogmorgo - rowing gears in a Grand Cherokee > Niquemarshall
11/16/2014 at 02:13

Find out how your system works. If you've got a blend door, that mixes air passing through the heater core with air passing around the heater core, it could be stuck. If you've got decent heat on both sides of the heater control valve, you probably don't have flow issue through it. If you're concerned about it, you can simply try bypassing it completely (it'll be the same as having it wide open) and seeing what that does.

I should have said this in my first post, but heat issues come from two fairly basic problems. Either you don't have coolant flowing through the heater core or you don't have air passing though it.

Heater hoses will get somewhat warm to the touch being connected to the cooling system, but if they're the same temperature as the rad hoses after you start your engine cold and warm it up until it hit operating temperature, then it's not a coolant flow issue. If they don't get to the same temperature more or less at the same time, then you have a flow issue and either you have a heater flow valve stuck shut or a clogged heater core. Test the temperatures of the heater hoses as far away from the engine as possible. See if parts of the interior get warm near where you know the heater is, if you can.

Air coming out of the vents doesn't mean it's going trough the heater core. Finding out how your system works (like I said above) will be helpful. Do you have a blend door? Do you perhaps have a cabin air filter?

gogmorgo - rowing gears in a Grand Cherokee > Niquemarshall
11/16/2014 at 02:16

Typically if you got vacuum in the temperature control, you'd also have it for vent position. With minimal vacuum, a system should default to a particular vent position, typically defrost for safety's sake. A clear windshield is better that toasty toes.

Niquemarshall > gogmorgo - rowing gears in a Grand Cherokee
11/16/2014 at 05:15

im sure theres a blend door. Haven't checked cabin filter either

Niquemarshall > gogmorgo - rowing gears in a Grand Cherokee
11/16/2014 at 05:16

one thing i did notice was that the vac hoses didnt seem to pull very hard

73maverickguy > gogmorgo - rowing gears in a Grand Cherokee
04/19/2016 at 23:41

So what about both heater hoses being hotter than rad hose and very little heat coming from heater?

gogmorgo - rowing gears in a Grand Cherokee > 73maverickguy
04/20/2016 at 08:24

Plugged heater core? Bad blower motor? Stuck blend/directional door?

I’m no expert, and but usually the heater system is pretty simple. You pump hot coolant through the heater, and then blow air through that and direct it around the cab. If air is going where it should in the quantity you should, either there’s no heat to the heater or air isn’t going through it. If there’s no air moving around it’ll be an issue with the blower fan. If the air’s not going where it should then you'll have an issue with blend doors.