Interior heating problems - Heat not coming out as hot as it should be

[BobLoblaw]

Hey guys,

 

I posted this problem at another Nissan site, but you guys are more reliable so I thought I'd ask here too.

 

My 1990 Maxima does not seem to be pumping out heat the way I want it too. [Definitely nowhere near as hot as my Pathy!] Is there anything I can do to fix this? What could be wrong?

 

I should also mention that the Maxima has auto climate controls and they seemed to work fine in the summer with the A/C. Now that it's cold, I turn it up to 32C (which is max heat), and it just comes out moderately warm. Please help!

[silver97ex]

Does the temp gauge go up or is that low too? Possible stuck thermostat, low on coolant?

[BobLoblaw]

Hey guys,

 

I posted this problem at another Nissan site, but you guys are more reliable so I thought I'd ask here too.

 

My 1990 Maxima does not seem to be pumping out heat the way I want it too. [Definitely nowhere near as hot as my Pathy!] Is there anything I can do to fix this? What could be wrong?

 

I should also mention that the Maxima has auto climate controls and they seemed to work fine in the summer with the A/C. Now that it's cold, I turn it up to 32C (which is max heat), and it just comes out moderately warm. Please help!

 

 

Yup, the temp gauge is fine. It's pretty frustrating. It's getting colder and I'm driving with minimal heat now!

[94extreme]

sounds like possibly a shot heater core.

[5523Pathfinder]

Grab the haser core hoses and see how hot they are. Has the coolant been service recently. There is a air relief plug that can be removed and "burp" the air out. Sounds like a thermostat might be stuck. Also, if it was serviced, that the water to coolant ratios is correct.

You may have a mode door stuck. Look under the dash and you will be able to notice the motors operate as you push different buttons. Make sure the motors have full movement, and go from there.

[BowTied]

I don't know maximas, but this is often the sign of a stuck thermostat as noted. This is especially likely if the cooling system is overdue for maintenace and/or the thermostat was a cheap crappy one.

 

The ratio of coolant to water, even straight coolant or straight water would not affect the air temperature, the thermostat will still operate the same and control the same temperature. This would affect the freeze or boiling temperature though of the coolant.

 

A control valve on the heater core hoses or a HVAC control system is a possibility.

[87pathy]

remember pathy's have kick ass heaters

[MY1PATH]

The ratio of coolant to water, even straight coolant or straight water would not affect the air temperature, the thermostat will still operate the same and control the same temperature.

that is incorret, "coolant" is not as thermal effecient as water. It will heat up faster and the thermostat will reach full open sooner. If there is too high a water ratio and the weather is cold enough the thermostat will remain closed and will still not get warm enough becasue there is still water going thru the heater core and thru the jiggle valve.

if the engine is colder the heater core is colder and so is the hot air.

[edicer2]

my parents landcruiser had the same problem and it was the thermostat so check it if u can.

[BowTied]

that is incorret, "coolant" is not as thermal effecient as water. It will heat up faster and the thermostat will reach full open sooner. If there is too high a water ratio and the weather is cold enough the thermostat will remain closed and will still not get warm enough becasue there is still water going thru the heater core and thru the jiggle valve.

if the engine is colder the heater core is colder and so is the hot air.

 

 

Assuming we are talking about an unmodified engine and cooling system in a proper state repair and adequate design capacity to cool the engine, we may have to respectfully disagree here.

 

Water, coolant, or a mix thereof in the engine water jackets will all be heated during engine operation. While the three fluids may have slightly different thermal properties, I contend that the differences for the practical purpose at hand (hot air out of the heater core) is not significantly different. Where you may be looking at the properties of these fluids and seeing a difference is in lowered freezing and elevated boiling points.

 

Assuming we are not talking about a vehicle in extremely cold climates where the heat dissipation through the engine block exceeds the rate of heat output to the fluid in the water jackets of the engine (and that is pretty darn cold!), the temperature of the fluid will continue to rise as the engine operates regardless of how “thermal efficient” it is (the time it takes to heat to a certain point may be slightly different, sure). Once the engine has heated the fluid to the temperature at which the stats open, ie 180F, the fluid moves to the radiator where it is cooled and then returns to the engine. This cycle continues and the stat regulates the temperature of the fluid at the stat’s rating within the manufacturing tolerances of the stat. So, sure, it may take more or less time to obtain heat depending on the fluid, but the heat will come if everything is functioning correctly.

 

 

EDIT

In re-reading your post, I think you may be suggesting that the addition of the heater core fan to the cooling system may be removing too much heat from the system causing the thermostat to close. If this happened, then there would still be heat coming out of the heater core, but the heat would cycle with the engine temperature.

 

The jiggle valve is used to release trapped air and shouldn't impact the coolant temperature or stat operation. The amount of fluid bypass is negligible unless the capacity of the system is right on the edge of acceptable (ie poor maintenance or poor design).

Edited November 28, 2008 by BowTied

[MY1PATH]

ok me (and you) have found a tangent lol that asside I donnot think that izz the problem. lol

we could state our views all day but I'd like to find this guys sollution. ( which I'm not full of ideas for since my heat worked better immediately after changing themostat)

[BobLoblaw]

ok me (and you) have found a tangent lol that asside I donnot think that izz the problem. lol

we could state our views all day but I'd like to find this guys sollution. ( which I'm not full of ideas for since my heat worked better immediately after changing themostat)

 

Thanks for everyone's help!

 

Okay, I did a bleeding of the system it didn't appear to change anything significantly. I hope to replace the thermostat soon and I'll let you know how that goes. Do I need some liquid gasket to do this job properly? Is so, is there a certain kind that is best?

[pktzygt]

Thanks for everyone's help!

 

Okay, I did a bleeding of the system it didn't appear to change anything significantly. I hope to replace the thermostat soon and I'll let you know how that goes. Do I need some liquid gasket to do this job properly? Is so, is there a certain kind that is best?

 

Thermostats come with temperature ratings. The rating will tell you when it opens up. If you drive in the desert, you're going to want one that opens up lower. If you drive in snow 36 days a year you want one that will open up at a higher temp so that your heat will get hotter. I'm from Washington DC suburbs so i have one at a middle temp range. Just pick one based on driving habits and it should have a gasket with it and if not the parts store should have one. Pick up a chiltons manual, it should lay out everything I told you alot beter than I could.

 

Good luck.

 

By the way, MAXIMA.ORG has some very knowledgable people on it. It seems that us nissan people have to become a little knowledgable and inventive due to lack of aftermarket support for our cars. I have a maxima buddy on that site with a supercharged max who knows all kinds of stuff about maximas that you wouldn't believe

Edited December 2, 2008 by pktzygt

[BobLoblaw]

Thermostats come with temperature ratings. The rating will tell you when it opens up. If you drive in the desert, you're going to want one that opens up lower. If you drive in snow 36 days a year you want one that will open up at a higher temp so that your heat will get hotter. I'm from Washington DC suburbs so i have one at a middle temp range. Just pick one based on driving habits and it should have a gasket with it and if not the parts store should have one. Pick up a chiltons manual, it should lay out everything I told you alot beter than I could.

 

Good luck.

 

By the way, MAXIMA.ORG has some very knowledgable people on it. It seems that us nissan people have to become a little knowledgable and inventive due to lack of aftermarket support for our cars. I have a maxima buddy on that site with a supercharged max who knows all kinds of stuff about maximas that you wouldn't believe

 

 

Well, thanks for the help guys. Do you guys know how to bleed the heating/cooling system? I might try this before I make the thermostat change but I think I'm going to try to change the thermostat tomorrow because it will only be -5C. It has been -25 --35C for about 3 weeks; I'm not doing car repairs in that temp with no garage! But if you know how to bleed a system, please let me know. I only want to change the thermostat if I have to.

 

Are there any standard steps to follow when changing a themostat? Should the car be cold? I've never done one before but I can't image it would be that hard.

Edited December 29, 2008 by BobLoblaw