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Cold Cabin, Heater works in spurts.
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=59795		 Page 1 of 2
Author:  racertracer [ Wed Mar 30, 2011 5:59 am ]
Post subject:  Cold Cabin, Heater works in spurts.
Any help in deciphering the following issue would be appreciated.

My heater is blowing cold air when I floor the accelerator.

Three weeks ago I replaced my thermostat with the OEM version.

I have been experiencing frigid spurts of air in the cabin during the first 20 minutes of warm up.

While traveling at 30 MPH the heater works fine and I can feel the cabin beginning to warm up, but if I give the turbo a small amount of boost the heater begins to blow frigid air.

Heat begins to returns while traveling at 30 MPH again, all this while the temp gauge is fixed a hair to the left of the half way mark.

So If I punch the accelerator pedal to make my way onto fast moving traffic, cabin heat is reduced and I get a burst of frigid air. It slowly begins to return after I let off of the accelerator pedal.

Temp gauge is at half way mark always.

This happens only during the first 20 minutes of warm up, after that all is normal.

This did not happen when I had a failed thermostat, my heater worked fine after reaching temp.

Could an air pocket left in the cooling system when I replaced the thermostat be the cause and if it is how do i get rid of it?
Author:  dkenny [ Wed Mar 30, 2011 8:34 am ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
I would suggest checking your vacuum lines..especially the one that control the blend door.

-dkenny
Author:  racertracer [ Wed Mar 30, 2011 1:51 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Thanks Dkenny, I just checked and unless I missed one, the vaccum lines check out ok.

Anyone else experience this behavior when they swapped out their thermostat?
Author:  patmaz [ Wed Mar 30, 2011 1:58 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Yes an air pocket would definately do that,i would open it back,and bleed it out...Simple fix. :wink:
Author:  racertracer [ Wed Mar 30, 2011 2:03 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
How do i open it without letting more antifreeze out?

If you mean unscrew the cap on the plastic coolant reservoir to let the air out, I have done that many times.

I was informed that air pockets in the cooling system have many times caused cracked cylinder heads and that the best way to get the air out, is to put it on a coolant flush/changing machine, is this true?
Author:  Sir Sam [ Wed Mar 30, 2011 2:04 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Sounds like you have air trapped in the system, try to top it off and bleed it out some more.
Author:  patmaz [ Wed Mar 30, 2011 2:09 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
You simply open the the cap,start the engine and let it get to temperature,i know it can take a while for a crd,but when its going to be at normal temp,you should see bubbles in the anti-freeze liquid,it might also spit some out,then when no more spit or bubbles,just put the cap back on,and it should be allright,the problem you have is creating pressure in the system because of the air cauht in it,so pressure is not steady.Try it and let me know! :wink:
Author:  racertracer [ Wed Mar 30, 2011 2:16 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
I keep opening and removing the cap and lots of air pressure comes out, I've done it about 10 times now.

If I let it run with it off will it ever reach high temp?

A relief valve at the highest point on the cooling system would probably solve this problem.
Author:  racertracer [ Wed Mar 30, 2011 2:21 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Here's word to the wise to those of you that have done your thermostat, coolant change, timing belt work or any other work that involved draining your coolant, make sure you have no air in the system because it could be the cause for a cracked head.
Author:  patmaz [ Wed Mar 30, 2011 2:22 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Yes sir a relief valve would solve that for sure,that is a real good idea,and yes it will get hot enough to bleed itself,you might just need to keep it up like to 2000 rpms for like 5 mins,its about the only way i can think of for now,the easiest one at least :(
Author:  racertracer [ Wed Mar 30, 2011 3:06 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Thanks Patmaz,

You have experience with cooling systems?
Author:  patmaz [ Wed Mar 30, 2011 3:22 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Yes sir been a mechanic for the last 18 years and dad was a mechanic for almost 50 years so i kind of know a bit about some tricky stuff :lol: and did it work for your jeep?where you able to bleed it? :wink:
Author:  racertracer [ Wed Mar 30, 2011 3:29 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Yes.

The crd is running and showing signs of bubbles coming from the small 3/8" conenctions on the side of the coolant bottle.

Thank you and welcome to the board.
Author:  racertracer [ Wed Mar 30, 2011 3:35 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Anywhere near NYC ..... care to do a timing belt, I'm at 98,500 miles?
Author:  patmaz [ Wed Mar 30, 2011 3:38 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
:wink: thanks!ive been here for a while but never took the time to introduce myself,i love this forum so much!and then i saw your post so i couldnt let a crd bro in trouble :lol: so i decided to show up and help,happy to see its working :roll:
Author:  patmaz [ Wed Mar 30, 2011 3:41 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Oups,would love too but im up north a liitle town 10 mi from montreal,yes another canadian :lol: sorry bud,except if you plan on a little trip hahahaha :D
Author:  racertracer [ Wed Mar 30, 2011 3:47 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
A bit too far for a Tbelt, but I do visit the old Oratory in Montreal to ask brother Andre for a few prayers now and then. It.won't be in the near future though so I may be doing the belt work myself.
Author:  patmaz [ Wed Mar 30, 2011 3:56 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Glad to see you came here,montreal is a nice city,of course weird stuff happens like in every big places,but its a nice place to visit at least once,and for sure if you ever come back aroud,make sure you let me know so i can introduce you to some jeepers up here a have a good time :D !
Author:  racertracer [ Wed Mar 30, 2011 4:02 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
Sure, I got the first round.
Author:  papaindigo [ Wed Mar 30, 2011 5:00 pm ]
Post subject:  Re: Cold Cabin, Heater works in spurts.
There is more or less a bleed valve high up in the system. It's the plug on the passenger side of the radiator (if the pictures are working see viewtopic.php?f=5&t=56486&p=628305&hilit=citric#p628305). Turn that plug ccw to 4 o'clock and pull straight up to remove but ONLY on a cold engine and then ONLY after opening the cap on the plastic tank. Fill the system from the plastic tank on the firewall (this functions as the "top" of the radiator and is where the pressurized radiator cap is located) until fluid comes out of where you removed the plug. Reinstall the plug and add enough more fluid to the tank to about 1/2 inch or a bit more above the tank seam. Drive long enough to run at full operating temperature to completely purging the system (about 15 minutes). Let engine fully cool, over night is ideal but several hours will do in a pinch, and add more fluid to the tank if needed; the level should go down a bit but not much (about 0.5 to 1 quarts worth at most). If the fluid level does not go down you may have a faulty radiator cap that needs replacing; if the cap doesn't operate currectly in the appropriate pressure range it is possible the system is not properly purging. That should do it but best glance at the fluid level after the next couple of drives to be sure.

If you have air pressure escaping when you open the plastic tank cap the engine and coolant are too hot. Opening that cap on a hot or even significantly warm system breaks the pressure/vacuum loop that pushes air out of the system thru the tank as the engine heats and pressure rises and pulls fluid back into the engine to replace that air as the engine cools and pulls a bit of a vacuum in the cooling system. Bottom line the system is designed to purge air thru the plastic tank as the system heats and cools with the system not being opened.
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