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[5th/miller]

Radiator is full and lines to and from heater core are warm. What else should I look at? Is there a vacuum actuated door to allow heat through in the heater box? Thanks for any input

[Dippy.org]

[5th/miller]

84 5th Ave

[79dodge4ever]

are the lines to the heater warm or very hot? its probably something to do with the blend door

[5th/miller]

Felt like dame temp as radiator hose. Was after sitting 20-30min. Ran to get something out of car and decided to see if low on coolant or if hoses were cold

[lsm360]

My guess is it is the blend door. I don't recall if a '84 Fifth is vacuum actuated. If so, probably one of the hard vacuum lines has come unconnected or one of the rubberish connectors has disintegrated over time. Both are commonly the problem when you have no heat and there isn't a leak of the heater core. I had both issues when I didn't have heat.

[Ark]

Blend door is my best guess as well. I don't know which position it defaults to when it loses vacuum, but if the mode door was bad it would default to the defrost vent.

Are the coolant lines warm all the way up to the firewall? The only other thing I can think of is an issue with the coolant valve.

[fifthcrunch]

I'll chime in, probably the blend door, which is vacuum actuated, so check vacuum lines and connectors.  Also could be bad check valve or the heater control valve under the hood or vacuum to it.  Another possible is a plugged heater core.

[5th/miller]

Both heater core hoses close to firewall are warm or same temp as rad hose when I checked. It was cool air coming from vents. I figured it would be the door you guys mentioned. Thanks for the input

[8D5 Gran Fury]

My guess is it is the blend door. I don't recall if a '84 Fifth is vacuum actuated. If so, probably one of the hard vacuum lines has come unconnected or one of the rubberish connectors has disintegrated over time. Both are commonly the problem when you have no heat and there isn't a leak of the heater core. I had both issues when I didn't have heat.

You don't need heat in Florida, Larry!

[lsm360]

You don't need heat in Florida, Larry!

Lol, not very often. But working nights like I do so often, it is occasionally in the 40's when I leave, and sometimes 30's. And, even when it's 50's I like to drive with my window down and heat on.

[5th/miller]

Heat worked on the way home from work

[MoparDan]

Heat worked on the way home from work

Was your fan not working or just not getting any heat out of it? my 600 have an issue with the fan: had to run it on one of the higher speed or it would sound like something was banging hard against something else. it stopped working completely one very cold January morning until I hit a huge pot hole (that I didn't see) and started working again and I never had another issue with it. Also is your thermostat the right temp? they sold me the wrong one once and all it did was blow cold air until I got the right temp one.
Just a few thoughts

[Chavlics]

Couple years ago in January my heat just stopped working completely wouldn't turn on or anything. Took it to a shop and they told me it was the actual piece where the bush buttons and temp slider are on the dash. Went to the junk yard and bought the whole piece for 5 bucks. Changed the piece (wish I knew what it was called) and it worked fine after that.

Then this summer I noticed that my heat was always on defrost even when it was supposed to be off. Push vent or bi-level and nothing but floor and window heat. Turns out it was what lsm was talking about. The vacuum connector disintegrated and crumbled to pieces, replaced that and now my heat works like it should     

[fifthcrunch]

The Great Connector Crumble.  Mine was also defaulted to defrost.  2 connectors were crumbled and the check valve was bad.
What I also found is that a very small rubber vacuum hose will connect the plastic hoses if you don't have a stock connnector (I had a lot of trouble getting the old hoses out of and into connectors).  I don't remember what the size on the hose is, but most parts stores have vacuum hose.  I replaced the check valve with a Volvo one, since I was getting some parts off a Volvo down at the yard.

[Chavlics]

The Great Connector Crumble.  Mine was also defaulted to defrost.  2 connectors were crumbled and the check valve was bad.
What I also found is that a very small rubber vacuum hose will connect the plastic hoses if you don't have a stock connnector (I had a lot of trouble getting the old hoses out of and into connectors).

Yup here's mine. Now I never have to worry about a connector failing ever again.