New water pump, thermostat. Heater blowing tepid to cool air since replaced.

Firstly, a thermostat that opens quicker will not give you better heat. Your heater core may be partially plugged causing a low flow issue. Another area to check would be the water pump impeller for corrosion or slipping on the shaft. Does the vehicle's cooling system operate well otherwise?

Your problem is a stuck open, or missing thermostat. Replace the thermostat, and your problem should be solved.

make sure all the air is bleed from the cooling system and its full. if this is good then you may have a water pump problem like worn impellers or a broken water pump not circulating the coolant.

My 2006 f-150 4.2L 113,000 miles heater blows cool when at Idle ,But when driving the heater blows hot. Change thermostat change water pump change the Rad. change the blend door motor
flush the block bleed the system add new green coolant. After all that still blowing cool air at Idle. What is causing this problem.

hi there it sounds like the matrix has gone it is at the back of the centre panel at the bottom when the engine is hot touch the matrix to see if its warm

The brown looking chiffon could be oil in the water. However, if you are sure the system is ok then I would check the actuator door motor on the heater and make sure it is allowing the heat into the car. Seems as if you have done as much as you can.

First, start by replacing the thermostat. It's located under the coolant filler cap / thermostat housing on a 2.4L dohc engine block on the upper left (passenger side)of the engine. We just replaced one in ours, but when we took the thermostat housing off, we discovered that the thermostat had broken/exploded, and that the lower thermostat spring and retainer were probably stuck inside the engine cooling galleries. We ran the car without replacing the thermostat, but it did not improve. The engine was still getting hot, and the heater blower still wasn't blowing hot air. We're going to try to replace the thermostat with the correct one (parts place gave us the wrong one and it didn't fit at all...), bleed the air out of the system again and see if there's some kind of link to there having to be a thermostat in the system. If that doesn't fix it, I'll have to look at the water pump to see if it's actually moving the water or not. If the water pump isn't functioning, the water isn't getting moved from the hot block to the radiator (where it's cooled through the radiator and goes back into the suction side of the water pump). If the pump is fine, and the new thermostat doesn't fix the problem, we'll have to investigate the possibility that the thermostat parts that got into the water galleries is somehow restricting the cooled water flow back into the engine, and that will be an expensive fix, I presume. Like all other cooling system problems though, start with replacing the thermostat. It's fast, cheap and will let you know where to look next if that doesn't fix it, but that problem is usually only a thermostat issue.

Hello...

One of 3 things could cause this, that I know. The thermostat has been installed backwards. The water pump broke soon after install. Due to it being a rebuilt one. And a small clog in the heater core. All of these things are easy to fix.

Good Luck...

These had a problem with getting air pockets in the heater core, because it sits lower than the engine. if the cooling system is rusty, and hasn't been serviced regular, the core might be part-pluged or pluged.

Sounds like a thermostat sticking. Some things to do. First check coolant level is up and moving. Second (most likely), change thermostat. Very easy fix for backyard mechanic. Make sure to put thermostat in so water flow is correct direction. Look for arrow on side of thermostat. Next, is belt to water pump loose. Another easy fix in most cars.