No Heat... '94 Ls400

[HOTSANDRAIL]

Hello Everyone!

I've been hanging around here for a while and just joined up yesterday. I have a LX450 and my Wife has a LS400 I've really learned alot and have received some helpful advise from you guys and I'm needing it again today.

First off I did do a search but still need your help!

On the LS400 the heat stopped blowing out hot. I replaced the shut off valve on the firewall where the cable hooks up to and it is working properly. I also changed the thermostat and coolant and filled to the proper level however still no heat!

At start up I can almost feel luke warm air but it turns to cool and stays cool even when driving. The blower is blowing as it should however I'm just not getting any hot air. The wind chill is 8 degrees this morning and my Wife Needs HEAT!

Any ideas as to what I should do next?

As always thanks for the help!

Mike

[wwest]

Hello Everyone!

I've been hanging around here for a while and just joined up yesterday. I have a LX450 and my Wife has a LS400 I've really learned alot and have received some helpful advise from you guys and I'm needing it again today.

First off I did do a search but still need your help!

On the LS400 the heat stopped blowing out hot. I replaced the shut off valve on the firewall where the cable hooks up to and it is working properly. I also changed the thermostat and coolant and filled to the proper level however still no heat!

At start up I can almost feel luke warm air but it turns to cool and stays cool even when driving. The blower is blowing as it should however I'm just not getting any hot air. The wind chill is 8 degrees this morning and my Wife Needs HEAT!

Any ideas as to what I should do next?

As always thanks for the help!

Mike

If you turn the controls to MAX HEAT, >84F, all of the sensors will be bypassed and the servomotors "blindly" driven into the maximum heating position. If the hot water flow valve is like my 92 LS you can even check that the remix/reheat vane/door is "swinging" to the max heat position by watching the push/pull cable on the water valve move to fully open.

Does the blower increase speed as you raise the "target" setpoint?

[HOTSANDRAIL]

Does the blower increase speed as you raise the "target" setpoint?

Thanks for your quick response!

This may be a stupid question but...raise the "target" setpoint meaning adjusting the temp setting from 65 (cold) to 85 (hot) OR are you asking about the low/med/high blower settings? The blower motor works properly when using the low - high settings. When adjusting from cold to hot or vice-versa I can see and hear the valve opening and closing as it should.

Could it be a relay or fuse keeping it from blowing out hot?

[larryp]

When coolant level is low, no heat will come out. Reservoir may show proper level but coolant level in engine may still be low. Remove coolant fill on thermostat housing and check level there. If low, add more. May have air trapped in system. Mine exhibited the exact same symptoms when my water pump was leaking. Car never ran hot, but wouldn't blow warm air because there was not enough coolant to heat up the heater core.

Good luck. No fun without heat.

[HOTSANDRAIL]

When coolant level is low, no heat will come out. Reservoir may show proper level but coolant level in engine may still be low. Remove coolant fill on thermostat housing and check level there. If low, add more. May have air trapped in system. Mine exhibited the exact same symptoms when my water pump was leaking. Car never ran hot, but wouldn't blow warm air because there was not enough coolant to heat up the heater core.

Good luck. No fun without heat.

Thanks for the info however I have the proper amount of coolant so that's not the problem. As I mentioned in my previous post the shut off valve in the engine compartment is new and working properly as well, the thermostat is new.. I'm thinking maybe the relay is bad?? Any other thoughts what else it could be before it goes to the shop?

Thanks!

[wwest]

Strange as it may seem you may have vapor lock. Sometimes a large air bubble will form in one of the heater hoses and basically block most of the water flow. The only procedure I know to move the bubble downstream and out is to remove the end of the water heater RETURN hose and let the coolant free flow into a bucket while being sure the radiator remains filled.

[HOTSANDRAIL]

Strange as it may seem you may have vapor lock. Sometimes a large air bubble will form in one of the heater hoses and basically block most of the water flow. The only procedure I know to move the bubble downstream and out is to remove the end of the water heater RETURN hose and let the coolant free flow into a bucket while being sure the radiator remains filled.

You're right..strange however it makes since!

I'll give that a try today. Again thanks for everyone's help and thanks for welcoming a new member.

I'll keep you updated, meanwhile keep the ideas rolling in...