Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: 72 watch on January 06, 2011, 05:35:27 PM

Title: heaters blowing warm to cold
Post by: 72 watch on January 06, 2011, 05:35:27 PM
hi everyone im new . i have just brought a wrangler jeep on a 93 plate 2.5 petrol. sqaure headlight job.  i noticed the heaters were blowing luke warm and it takes a few seconds or so to start from hot. so i have changed the thermostate and gaskets today. bled the system and they are still the same.also i changed this also because of the starting prob when the engine is warm as i thought that the engine tempeture sensor is detecting the water is not hot and bringing the auto chokes in when engine is warm.  so has anyone have any idea how to get the heaters hot. i did think maybe taking the conventional fan off and put eletric ones on. comments plz
Title: Re: heaters blowing warm to cold
Post by: Panic mechanic! on January 06, 2011, 05:39:36 PM
both of the yj's I owned have had furnaces for heaters, have you got the right thermostat fitted, is the engine coming fully up to temp?
Title: Re: heaters blowing warm to cold
Post by: Cockney Boy on January 06, 2011, 05:53:18 PM
Have you reverse flushed the Heater matrix? I did this on my old YJ and the water was not a very nice clour (dirty brown with black bits in) so i changed the matrix and it solved to warm air problem. On inspection the matrix was shot and only good for the bin.
Title: Re: heaters blowing warm to cold
Post by: 72 watch on January 06, 2011, 06:02:47 PM
both of the yj's I owned have had furnaces for heaters, have you got the right thermostat fitted, is the engine coming fully up to temp?
[/quote hi the temperture gauge is not working and some one has fitted anew sensor in the housing and i tested the connection and there is power there so dont know y the gauge is inoperative were the thermostate fits into a slot in the engine i put some silicon round there to help seal the thermostate .as for the thermo it came with the car all in the box.
Title: Re: heaters blowing warm to cold
Post by: Panic mechanic! on January 06, 2011, 06:03:29 PM
my first 2.5 did have a slight problem when I first got it , in that the thermostat houseing had some corrosion in it that meant the thermostat was actually constantly being  by passed due to corrosion from one gallery into the other, once i replaced that it was no longer a prob
Title: Re: heaters blowing warm to cold
Post by: Panic mechanic! on January 06, 2011, 06:04:35 PM
where are you located?
Title: Re: heaters blowing warm to cold
Post by: 72 watch on January 06, 2011, 06:06:22 PM
hi i could try flushing the matrix but i did notice that the hoses arnt hot only warm this is all water hoses
Title: Re: heaters blowing warm to cold
Post by: Cockney Boy on January 06, 2011, 06:11:27 PM
hi i could try flushing the matrix but i did notice that the hoses arnt hot only warm this is all water hoses

Ah then yes it could be the Thermostat. I did change mine as a matter of course.
Title: Re: heaters blowing warm to cold
Post by: Mike Pavelin on January 06, 2011, 08:20:41 PM
hi everyone im new . i have just brought a wrangler jeep on a 93 plate 2.5 petrol. sqaure headlight job.  i noticed the heaters were blowing luke warm and it takes a few seconds or so to start from hot. so i have changed the thermostate and gaskets today. bled the system and they are still the same.also i changed this also because of the starting prob when the engine is warm as i thought that the engine tempeture sensor is detecting the water is not hot and bringing the auto chokes in when engine is warm.  so has anyone have any idea how to get the heaters hot. i did think maybe taking the conventional fan off and put eletric ones on. comments plz
Check the viscous fan coupling isn't siezed solid.
Title: Re: heaters blowing warm to cold
Post by: Bubba on January 06, 2011, 10:25:40 PM
 :iagree:
Title: Re: heaters blowing warm to cold
Post by: 72 watch on January 09, 2011, 04:25:23 PM
both of the yj's I owned have had furnaces for heaters, have you got the right thermostat fitted, is the engine coming fully up to temp?
[/quote hi the temperture gauge is not working and some one has fitted anew sensor in the housing and i tested the connection and there is power there so dont know y the gauge is inoperative were the thermostate fits into a slot in the engine i put some silicon round there to help seal the thermostate .as for the thermo it came with the car all in the box.
  hi again i have flushed the matrix today like you said and lumps of brown thick sludge came out i could not blow down the pipes to start with but once the water started to move through it soon shifted it.the heaters are now red hot they start to burn your hand if kept there.thanx for that regards paul
Title: Re: heaters blowing warm to cold
Post by: Cockney Boy on January 09, 2011, 05:17:28 PM
Hi Paul,

It was me that sold the Jeep to you lol. I checked the Clocks so dont bother replacing them, so it is the sender unit. I made the same mistate of replacing what i thorght was the sender on the Thermostat housing, and when i re-checked the manual the sender is round the rear of the block. One easy way of testing the cable is to remove the spade conector from the sender and touch it on the block and get someone to see if the gauge moves.