Heater only works when pressing the gas?

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  #1  
Old 11-03-11, 05:32 PM
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Heater only works when pressing the gas?

I have a 96' Nissan Maxima. When the heater is on and I'm not pressing the gas pedal, luke warm air blows from the vents. When I press the gas, the air from the vents is nice and hot. There is no apparent change in how much air is blowing through the vents whether I'm gassing or not. It's just hotter. I am baffled.

There is plenty of coolant in the car, though I do have to top off the reservoir every month or two.

Any thoughts? Last winter was miserable.

Thanks.
 
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  #2  
Old 11-03-11, 06:52 PM
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why baffled? your water pump is spun by engine. more rpms=more rpms at pump=more coolant flow=higher temperature.

I'd say, either blockage somewhere, like enlarged proatate, and you have to push through, or your pump is getting there.
 
  #3  
Old 11-03-11, 07:11 PM
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So you suggest replacing the water pump?
 
  #4  
Old 11-04-11, 04:16 AM
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I'd start by cleaning the cooling system - radiator flush.
 
  #5  
Old 11-04-11, 07:18 AM
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Disconnect the heater hoses and flush heater core with a hose.
 
  #6  
Old 11-04-11, 04:19 PM
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Flushed the system and no change. Water pump?

Also, has anybody ever removed the thermostat housing on a 96 Nissan Maxima? Jesus. What tool do I need to loosen and then tighten the three nuts holding it on? Socket set won't fit, neither will a combination wrench.
 
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Old 11-04-11, 06:10 PM
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post picture. photobucket image code works well.
no, I suggest figure out if you have good coolant flow.
you can start with manually checking in and out hoses to your heater core. if they are the same temperature, then your heater core is no clogged. if one is colder - well, you got it.
next step is to see how well it circulates through your radiator.
next step is to check if your radiator is roughly evenly hot.
and if all this passes test, then it's your pump very likely. or, better off, a loose belt. some models have belt driven pumps. or, you can have timing belt, not chain, and either belt is stratched, or tensioner is loose.
have fun.
don't mention the name of The Lord Jesus Christ in vain.
 
  #8  
Old 11-04-11, 08:22 PM
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If you have to keep topping up the coolant reservoir.. you got a problem. You likely have an air pocket in the block and the water pump looses prime at idle.
Find where the coolant leak is and fix it. Then check for water pump efficiency.
 
  #9  
Old 11-14-11, 08:41 AM
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Wink did u flush the heater core?

u must remove the hoses from the heater core then connect a garden hose to the inlet,outlet,pipes turn hose on until u get a clear steady flow.then reverse to other pipe,do the same.reinstall hoses. u should be ok. very common problemespecially on chrysler.
 
  #10  
Old 11-15-11, 11:44 PM
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Red face

I bought a drill pump for about $10 at hardware store when I had same problem with an old Dodge Caravan. Bought a couple of jugs of CLR ( calcium ,lime, rust remover) and dumped them into a pail. Removed heater hoses at heater core and attached garden hose type from pump to heater core with hose clamps. One hose in from pump, and the other out and back to pail. Plus hose on suction side of pump to pail. Kept circulating CLR through core, then would plug return hose to let it sit in core for a while. Then after circulating one way, I reversed the hoses to circulate through core other way and let sit for a few minutes as well. I then made sure core was full, plugged return hose and let it sit in the core overnight. Next day, flushed it again a few more times each direction, then drained it, and refilled system and let run well with heater on to remove all air. Let rad fan come on 2 or 3 times and watched flow, and topped up as needed. It did the job. Maybe not 100%, but 100% better than it was, and was still good 2 years later when I sold it.
 
  #11  
Old 12-06-11, 04:55 PM
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Thanks for the help so far.

Update:

I flushed the heater core, coolant system, and while flushing the coolant system found that the previous owner could have tightened the bolts for the thermostat housing tighter - I believe this was the cause of the coolant leak.

So - coolant system and heater core are flushed and coolant leak is fixed. Heat still only blows hot air when I press the gas.

As the temperature has dropped, I noticed the car squeals for a few minutes when I first start it up, particularly when I press the gas. The belts are new and tightened properly, and I'm wondering if this is related?
 
  #12  
Old 12-06-11, 07:06 PM
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WarnLot,
I had a van that would squeal every morning for as few miles, once it starting getting cold out. As it turned out in my case, it was a bad Idler pulley. You might want to check that, it started taking longer and longer for the squealing to stop.
 
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Old 12-06-11, 08:03 PM
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Thanks Edward. A guy at work mentioned an idler pulley, and I was going to look in that direction, but just wanted to check and see if anybody thought it could be related to the heater issue.

Another thing just occurred to me: when I start the car, I can't turn the wheel for a few minutes until its warm. Power steering pump?

So am I driving a car with a ton of problems, or could the power steering pump be causing the squealing, and loss pressure to the heating system when I'm not pressing the gas?
 
  #14  
Old 12-06-11, 09:26 PM
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What kind of belt(s) are on your engine? One single long serpentine or other separate V belt style ones. Could be a slipping belt that drives both the power steering pump and water pump among other things if both share a common belt. Squeal can also be from the belt. Just some other ideas to consider.
 
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Old 12-07-11, 05:43 PM
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I have multiple belts, not a serpentine belt.
 
  #16  
Old 12-07-11, 08:43 PM
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All the belts are in good condition and tight right? There are alot of things going on that may or may not be related, but one common point can be drive belts. In addition you could always add some 'liquid mechanic' like a Lucas product to your power steering reservoir and see if that improves things or not as a start point on the power steering situation. Another point around the noise is the water pump. Are you sure it is not involved in the noise, and if some coolant leakage was from it if the front seal was starting to fail? Just another question, when warmed up does the engine temperature remain constant or also vary by engine speed?
 
  #17  
Old 03-11-12, 02:15 PM
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2granddaughters is right. You have an air bubble in the block. It's caused when your coolant gets low. Fix your leak and bleed the coolant system. Or you can check this theory by filling and bleeding the coolant system now. If it works, it will be ok until the coolant system gets low and causes the air bubble again.
 
  #18  
Old 03-11-12, 02:43 PM
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Air locking

I have a 96' Nissan Maxima. When the heater is on and I'm not pressing the gas pedal, luke warm air blows from the vents. When I press the gas, the air from the vents is nice and hot. There is no apparent change in how much air is blowing through the vents whether I'm gassing or not. It's just hotter. I am baffled.
I had a similar problem with a Mitsubishi of ours last year. I'd topped off the radiator and the ensuing air lock caused the heater to stop working - only blowing warm to cold air even though the temp gauge read fine. I'm now a person who attempts to avoid removing radiator caps in favor of maintaining burp tanks. ;-)

I took that vehicle to our local autoshop who does tires, flushes, etc and had them flush the system. I got it back working fine and haven't touched the rad cap since.
 
  #19  
Old 03-11-12, 04:32 PM
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You have a circulation problem by giving it more acclerator you increasing circulation check the temperature of both heater hoses and upper and lower radiator hoses all should be at least 180 degrees or higher if they are hot then thermostat is open. Make sure system is full of coolant.I have seen where water pump impleller isn't tight on shaft causing low circulation.water pump would have to be replaced.a noisy belt on start up most time is not adjusted propertly.
 
  #20  
Old 03-12-12, 09:01 AM
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So far, everyone has focused on the engine cooling system.

While this is a possible culprit, there is another possibility to consider -- the blend-door in the HVAC system. The blend door controls the temperature of the air blowing through the vents. It is vacuum-operated and controlled by the temperature knob. If there is a problem with the vacuum lines, you can end up with a partially-operating door. It's possible that at idle, when you have high vacuum, the door gets stuck in the half-way position, leading to luke-warm air. When you press on the gas, the vacuum drops and the door moves to the full-hot position.

Set your temperature control knob to full-cold and compare the air temperature with what you get with the engine idling right now. If it's about the same, I'd have someone look into the blend door controls and see what's going on.
 
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