Heater Issues

[LS Jasper]

Hi all,

Cold weather has got me using the heater properly for the first time since buying my 1995 Mk3 LS back in April. When driving heater works ok, but when I stop at the lights, traffic etc it starts blowing out cold air - not nice on my toes on a cold morning. If I turn the blower down to minimum at the lights then I get the hot air back again. Once I start revving again I get full power and heat again.....

Any thoughts?

Jim

[ROYT]

Hi all,

Cold weather has got me using the heater properly for the first time since buying my 1995 Mk3 LS back in April. When driving heater works ok, but when I stop at the lights, traffic etc it starts blowing out cold air - not nice on my toes on a cold morning. If I turn the blower down to minimum at the lights then I get the hot air back again. Once I start revving again I get full power and heat again.....

Any thoughts?

Jim

Make sure coolant level topped up to max.

If still cool suggest faulty thermostat.....

[wow300]

sounds like low coolant as said

[sir john]

It will depend on what your temp guage is telling you. On an LS the guage on the dash should always read dead centre. No matter whether you are pushing it hard on a hot day or sitting in traffic in the snow.

Cool air coming from a car engine at full opporating temperature oints towards low coolant level. And that usually spells disaster not too far down the road if its not fixed.

Good luck. And let us know what the temp guage is doing while the air is going from hot to cool.

[LS Jasper]

Topped up the coolant but it only needed about 75ml - not enough to make that much difference. Kept an eye on the coolant level with the engine ticking over and no movement in the resevoir. By temp gauge, do you mean the outside gauge next to the clock or is there another heater gauge I should be looking at?

Cheers,

Jim

[beavisrules]

Temperature gauge just to the left of the rev counter. in main dash binnacle.

mine takes about 3-4 mins to reach 1/2 way , but is blowing warm air from just after the first 90 seconds.

Theres a few possibilitys as mentioned -

Thermostat stuck open(* favorite) , fans stuck on (you'd hear that though!!) or a heater unit malfunction - ie a servo/motor slipping.

ones you REALLY don't want but possible - water pump broken

lastly i guess it's possible for a electrical fault in the a/c controls to manifest this way?

[LS Jasper]

Nothing noisy going on. Temp gauge reaches the usual postion just below half way after about 5 mins. Not sure when I start to get warm air from cold but will check Could I have an air lock? I am planning to change the coolant soon as the car came with blue rather than the red coolant.

Haven't been out in the car this week as had a little sporting injury to my leg and so been laid up! Will have another check of possibles tomorrow.

Thanks for your suggestions!

Jim

[LS Jasper]

Also get a bubbling sound when I accelerate shortly after starting up. Read somewhere that this could indicate air in the heater unit. May be an airlock in my cooling system, particularly the heater unit. Would that result in cooler air being blown through the heater system when the car is stationary? When I accelerate does that result in increased coolant circulation? Although I have nothing to compare with I don't think even at max hot the system gets that hot.

Need to do full coolant change anyway so perhaps now is a good time???

Thoughts?

Jim

[sir john]

Air in the coolant was my first thought. It will definately result in the engine reaching full operating tepmp but cold or only col;d air coming from the air vents. Its an old trick when you suspect that the engine is losing water to turn the heater to max. If it doesnt blow HOT you are low on water and in for a head failure if you dont do something about it.

[itarumaa]

I did change the coolant without any ramps etc, just used the valve in radiator, quite easy and there are good instructions in the engine bay (sticker) how to bleed the system,

Mine has been perfect after the coolant change, it used to took quite much coolant, now almost nothing.

I changed the coolant from blue to red when doing the change, then I circulated enough coolant/water trough the system until the color changed from blue to red and that is basically it, if you want to do this 100% then you should open the valves in the engine block as well, but I do not see that this is necessary.

Do not use tap water would be my advice and make sure you get the right type of coolant.

[beavisrules]

I cant remember if the ucf20 has a radiator cap as well as a expansion tank cap.

If it does , it'll be worth checking the radiator cap seals under pressure.

the rubber seal and the spring deteriorate with age and can let water escape and sometimes air in.

[itarumaa]

I am quite sure that ucf20 does not have radiator cap at all.

[LS Jasper]

Did the full coolant flush last weekend. The pinkish stuff that came out was pretty grim. Quite a job to find both the drain valves either side of the engine block plus surprised that both needed different size sockets! Gave it a full flush too. Outcome - no change on the heater issue. Have read back on some older threads and now wished i had disconnected the in and outlet hoses to the heater matrix to check for any obstructions. My mechanic feels that there may be a flow obstruction which restricts flow during low revs. Other thread has Ruud disconnecting and flushing the heater without having to drain down and so that is my next plan.

All thoughts welcome.

Jim

[Chris Skelton]

Thanks, at least for reminding me to flush the system (AND to use distilled water in the rad, I recall?)

Must check to see if my recent service included this- doubt it did!

My heater is fine, but it helps to keep on top of things!

Good luck with your search!

[AdeV]

Thanks, at least for reminding me to flush the system (AND to use distilled water in the rad, I recall?)

Must check to see if my recent service included this- doubt it did!

My heater is fine, but it helps to keep on top of things!

Good luck with your search!

+1 ....

I need to get some antifreeze in mine, still haven't changed the water after doing the water pump/cambelt.... (oops)

[LS Jasper]

Wonder if running on LPG makes any difference? As part of the Prins system I have, there is now a T on the heater matrix inlet/outlet hoses in order to include the LPG system in the cooling process. Not sure if that T upsets the flow at low revs?

Also anyone have a view on whether running on LPG will increase the visible exhaust fumes when engine is idling? I have been experimenting, running on both LPG and petrol and I definately get more visible white exhaust emissions when idling at cold external tempretures. Any thoughts?

Cheers,

Jim

[LS Jasper]

Sorry - hit reply by mistake

[LS Jasper]

I think I have found the problem to my heater blowing out cool air when engine is idling. I have a PRINS LPG system which was fitted in 2003 and serviced in April 2011 - all works well. As mentioned in my earlier comment, the LPG system is linked to the cooling system in order to cool the LPG vaporiser by way of a T from the flow and one from the return into the heater matrix. When the engine is up to temp and the engine is idling the flow pipe into the heater matrix is hot, but the return up to the T is not. However, the return pipe into the T from LPG vaporiser is hot.

[AdeV]

I think I have found the problem to my heater blowing out cool air when engine is idling. I have a PRINS LPG system which was fitted in 2003 and serviced in April 2011 - all works well. As mentioned in my earlier comment, the LPG system is linked to the cooling system in order to cool the LPG vaporiser by way of a T from the flow and one from the return into the heater matrix. When the engine is up to temp and the engine is idling the flow pipe into the heater matrix is hot, but the return up to the T is not. However, the return pipe into the T from LPG vaporiser is hot.

It's actually to warm the vaporiser, not cool it (without heat, they frost up in no time & stop working).

[LS Jasper]

I think I have found the problem to my heater blowing out cool air when engine is idling. I have a PRINS LPG system which was fitted in 2003 and serviced in April 2011 - all works well. As mentioned in my earlier comment, the LPG system is linked to the cooling system in order to cool the LPG vaporiser by way of a T from the flow and one from the return into the heater matrix. When the engine is up to temp and the engine is idling the flow pipe into the heater matrix is hot, but the return up to the T is not. However, the return pipe into the T from LPG vaporiser is hot.

It's actually to warm the vaporiser, not cool it (without heat, they frost up in no time & stop working).

Thanks Ade, learning all the time! Any thoughts on what I can do to stop the draw to the vaporiser and away from the heater matrix at low revs??? Will contact the lpg installer tomorrow and see if he has any suggestions.

[AdeV]

I think I have found the problem to my heater blowing out cool air when engine is idling. I have a PRINS LPG system which was fitted in 2003 and serviced in April 2011 - all works well. As mentioned in my earlier comment, the LPG system is linked to the cooling system in order to cool the LPG vaporiser by way of a T from the flow and one from the return into the heater matrix. When the engine is up to temp and the engine is idling the flow pipe into the heater matrix is hot, but the return up to the T is not. However, the return pipe into the T from LPG vaporiser is hot.

It's actually to warm the vaporiser, not cool it (without heat, they frost up in no time & stop working).

Thanks Ade, learning all the time! Any thoughts on what I can do to stop the draw to the vaporiser and away from the heater matrix at low revs??? Will contact the lpg installer tomorrow and see if he has any suggestions.

Unfortunately, I can't think of anything simple; it sounds like you need a restrictor valve to divert more water through the heater matrix than through the vaporiser - if it's too restrictive though, you might end up with your gas valve freezing & the engine stalling (or, best case scenario, switching back to petrol).

[LS Jasper]

Disconnected the heater matrix and tried to flush it through. At first I couldn't get the water through but connected up a hand pump and forced the water through. Nothing obvious came out by way of an obstruction but water was passing through nicely. Filled it up with coolant, connected it back up and started her up and I now have hot air coming through normally! Must have been some sort of blockage. I have been out in her three times today just to check that it all still working! Kid with a new toy!

Cheers for everyones help.

Jim

[TrevorK]

I have a problem, if anyone has any ideas. Just bought 2005 LS430. The temp control on driver's side of centre console is the problem. If I set it at "cold" then cold air blows from everywhere, but as soon as I change it to 16 deg or above it just blows hot air, with no apparent regulation. The temperature I set it to doesn't seem to matter. It just keeps on blowing hot air until I have to open a window or turn back to "cold"

Anyone else experienced this and any suggestions would be most welcome

Trevor