Heat Troubleshooting

[Shlop]

Hey Guys,

So one of the major issues right now with my new to me 3rd gen 98 Limited, the heat is not working correctly. It takes forever to heat up, and when it gets to temperature it is luke warm, at best. It blows out the front, not sure about the back? Because the entire car fogs up immediately when its cold outside (like it has been lately) and not even anti-fog helps too much but i think that might just be because it's old and expired.

What might I be able to do to troubleshoot the issue and see if I can fix it myself?or just be able to find out and save on diagnosis if the job isnt within my realm of ability.

Any insight would be helpful, I'm a visual learner so anything that I do to my car i usually need a video or some reference. I would ideally like to come up with a Step 1, Step 2, etc plan to figuring out most possible issues, or just whatever sequence makes sense while I'm at certain points of the troubleshoot.

TYIA

 

[JoeT4R]

Hey Guys,

So one of the major issues right now with my new to me 3rd gen 98 Limited, the heat is not working correctly. It takes forever to heat up, and when it gets to temperature it is luke warm, at best. It blows out the front, not sure about the back? Because the entire car fogs up immediately when its cold outside (like it has been lately) and not even anti-fog helps too much but i think that might just be because it's old and expired.

What might I be able to do to troubleshoot the issue and see if I can fix it myself?or just be able to find out and save on diagnosis if the job isnt within my realm of ability.

Any insight would be helpful, I'm a visual learner so anything that I do to my car i usually need a video or some reference. I would ideally like to come up with a Step 1, Step 2, etc plan to figuring out most possible issues, or just whatever sequence makes sense while I'm at certain points of the troubleshoot.

TYIA

There could be a ton of different reasons. But let's start with the thermostat. Has it been replaced yet?

 

[the_welfare_wagon]

Grab the heater core lines once the car is fully warmed up. If the inlet is hot but the outlet is cold then you have a clogged heater core. That’s the easiest thing I can think of to rule out right off the bat


Sent from my iPhone using Tapatalk

 

[Shlop]

There could be a ton of different reasons. But let's start with the thermostat. Has it been replaced yet?

I have service records dating back to '08 with no mention of the thermostat or really anything obviously related to the heat

 

[Shlop]

Grab the heater core lines once the car is fully warmed up. If the inlet is hot but the outlet is cold then you have a clogged heater core. That’s the easiest thing I can think of to rule out right off the bat


Sent from my iPhone using Tapatalk

Awesome will go to rule that out first thing tomorrow then.

 

[Shlop]

Ok so with the responses and then having a direction on what videos to watch, I've come up with this plan for troubleshooting:

1. Coolant level check
2. Check valve function and hose temps towards the heater core to see if its clogged
3. Check Thermostat


Based on those results ill have to do either an air flush on the coolant lines, unclog the heater core, or replace the thermostat or any combination of some or all of those things

Am I missing a possibility?

 

[Bad Luck]

Ok so with the responses and then having a direction on what videos to watch, I've come up with this plan for troubleshooting:

1. Coolant level check
2. Check valve function and hose temps towards the heater core to see if its clogged
3. Check Thermostat


Based on those results ill have to do either an air flush on the coolant lines, unclog the heater core, or replace the thermostat or any combination of some or all of those things

Am I missing a possibility?

Could also be a problem with the temperature blend door or cabin temp sensor as well.

Also keep in mind that the temp gauge in the instrument cluster has a very wide range and will stay in the same spot from around 140*F to 220*F so it's not really a good way to gauge that the engine is at operating temperature. You really need an OBD scanner or similar to see engine temperature from the ECM. It takes my 4Runner about 10-15 minutes of driving to get the engine warm enough to have heat.

 

[nissanh]

After you get the engine to working temp, allow the water into the heater core. Check the temperatures of inlet (connected to the flow valve) and the outlet. There should be a significant temp difference if heat is removed at the heater core.

 

[phattyduck]

Another note -
Are you using the 'defrost' mode? If so, it automatically turns on the AC to dry the air.
Also, you should be using outside (fresh) air setting for most conditions. Recirculating is find while things are initially warming up, but otherwise you are just keeping all the moist air inside the cabin.

Possibilities:
- Mechanical issue (thermostat)
- Electrical issue (bad control unit)
- User error (wrong settings)

-Charlie