Manager Forum

Got a 2004 nissan altima s 2.5 liter. Car has no heat inside vehicle form ducts best temp is 52 degrees.... Customer claims car has been like this since new,Nissan said they could not do anything for him. That there is no problem; its normal.

This is the customer complaint. Let car idle with heater blower set at low,50 degrees,turn blower on high,ice cold air from ducts. Drive car,sit at light heat 50 degrees,start moving gets cold. This has been verified. He states that 3 other shops have changed the thermostat,no change.We checked heater hoses temp at core 120,at block 195, big drop in temps o both sides inlet and outlet at heater core. Disconnected heater hoses and back flushed heater core,plenty of flow...Vacuum sucked cooling system down refilled with coolant. Still no heat.
Disconnected blend door cable and manual moved it from hot to cold, still no heat?????????????????????????????????

Car engine gets hot and doesn't overheat.

I pull the return hose off the engine and start the car to see if coolant is actually flowing through the heater core and also what the temp of the water coming out of it. You can also see how much is flowing. If you have good flow with a good hot temp no heat out of the vents, and you know the blend door is functioning correctly, about the only option would be a heater core that is internally messed up and not flowing through much of the core. With the car running and the blower on high, put your hand in front of the vent while you are moving the temp lever from hot to cold and see if you feel any difference, also listen for the sound of the door moving from stop to stop inside the case. You should also hear a change in the sound of the blower when moving from hot to cold and back to hot.

If you raise the rpm do you get heat in the vehicle? do the heater hoses get to hot to hold? During this time what is the temp gauge reading? If temp is reading 200ish degrees and heater hoses are to hot to hold the issue is with the blend door. If the hoses are tepid than it could be a feed or suction issue. If the engine temp is low and the the thermostat is correct then the radiator may be to large and coolant will never reach temp. You will never attain optimum heat if the flow is inconsistent. Another issue here is an air pocket in the heater core. I've had some vehicles that i need to use the suction and fill tool to eliminate the air pocket or jack up the front of the car and rev the heck out of it to get the bubble out.

Ok list of other things we have checked.

Heater hoses near engine are hot to touch try to hold them by heater core,fire wall warm at bests. Disconnected hoses and started engine got flow at heater core..Ran a hose through heater core both ways got flow. Lifted front end of car 20 inchs and vacuum sucked system into a vacuum filled and used over flow bottle to top off coolant.

Second found heater blend door cable and deattached cable.Manually moved blend door from heat to a/c heard different pitch in blower sound on high and can hear a slight thump from duct. But air still blows cold. In either settings. Car idling or sitting at stop light slight heat from ducts. Raise idle or start driving fasts or slow,car gets cold air fro ducts......?????

I see you moved Heat/AC door. Did you move Hot/Cold door also? Maybe a dumb question, but wondered.

The way it sounds is a restricted heater core. A flow test with a hose is very misleading at best. At this point if it were in my shop a heater core replacement would be on the horizon.

yes hot cold blend door is the one we moved....

Do you notice any increase in air flow when moving from hot to cold? Possible it could have a blockage in the case itself causing an issue with no heat? Paper, pet hair, leaves, etc. Not sure how the air flows thru the box. Just a thought.

There is a TSB for poor heat for 2002 thru 2006 Altimas. A 50/50 mix of coolant/water is critical in this car according to Nissan. There is also a special coolant bleed procedure outlined in this TSB. Back to your problem of poor heat. Both heater pipes are on the same tank of this heater telling us there is "supposed" to be a baffle in that tank to direct coolant thru the heater core. If the baffle is missing then coolant would appear to be flowing good thru the heater. The only way I know of to check to see if the baffle is in fact there would require heater removal. Just another view I suppose but anything is possible. hth Jerry.

What if ya pulled the heater hoses and peeked inside with a boroscope? Just another thought.

By looking at the pipes a snake would have a hard time getting thru, lloks like 3 or 4 90 deg bends on each.

Ok we did everything as out lined in tsb with the bonus of raising front end,vacuum sucking coolant system and used a over the to radiator over flow.....

How about the air going by the code sides. Send a scope in to see what is going on.