I have no heat.

I recently made had a waterpump replacement done. I noticed i had no heat, so i changed several hoses connected to heater core. I disconnected the hose from the heater tube on water pump and found that no water was passing through the hose. What could be the problem? Thank you.

My car has 150000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
If a coolant hose is disconnected you can’t run the engine to determine whether coolant flowed or will flow. Often, after a cooling system is drained, if there is no heat, what has happened is air has gotten trapped in the system and is preventing coolant circulation. That’s why when coolant is added, any air purge ports provided in the system must be opened. If you don’t suspect trapped air, or you already remedied that, there are only several possible causes for no heat: there is a mechanical blockage in the relevant hoses; the water pump doesn’t work (your car would overheat of course), or somehow the pump outlet you describe is blocked; the heater control valve on the firewall is stuck closed, and/or the heater core is substantially plugged. To determine which of these is the cause, the recommended service is a no cabin heat diagnostic.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

If the heater core becomes clogged up, coolant cannot flow around the heating matrix, radiator and engine, and can therefore not be used to heat the cabin. If you suspect the heater core to be clogged, a flush of the system will be necessary to restore it to working order.
The most common reasons a Dodge Ram 1500 heater isn`t working are a broken heater blower motor, a problem with the thermostat, or a failed heater blower motor resistor.
Faulty heater cores and low or contaminated coolant levels often come hand in hand, and both issues may lead to your engine overheating and your heater not blowing hot air.
When the vehicle is at operating temperature feel the two hoses, the should be the same temperature. If one hose is noticeably hotter then the other then the heater core may be partially plugged or restricted.
Check the temperature of the heater inlet and outlet hoses by feel. (The air temperature around the hoses must be at least 85°F (24 °C).
Dodge Ram climate control reset instructions

Step 1: Turn your fan to the lowest possible setting. Step 2: Hold down the climate control/conditioning button for 10 seconds. Step 3: Let go of the button, then press and hold it again until the lights on the button start flashing. And that`s it!

If you find your furnace blowing cold air, you may have a dirty or clogged air filter. To make sure, remove the air filter and inspect it. If it`s clogged with dust, clean it with compressed air or wash it in warm water with mild soap or just buy a new one.
There are a few basic issues that usually lead to the blowing of cool air from one`s car heating system: There isn`t enough coolant in the engine. There is a problem with your heater core. Your thermostats are not working correctly.
Weak or no airflow. Cold air (not warm) coming through the vents when the heater is on. Coolant leakage visible inside the cabin or a damp smell.
The heater core will usually start to deform if air pressure reaches 50 PSI. Air pressure should never exceed 36 PSI. OTHER FACTORS TO CONSIDER WHEN REPLACING A HEATER CORE: • NEVER USE FORCE to remove the heater hose from the pipe.
When your radiator is cold at the bottom, it`s likely that there`s a debris blockage that`s restricting the flow of hot water to the whole radiator. Usually, the culprit of this particular problem is sludge, debris, rust and other bits of dirt.
​Heater Core and Thermostat Temperature Diagnosis:

190°-210°F Temp. reading at inlet means the thermostat is functioning properly. If temp. at outlet is 10°-25°F cooler than inlet, the heater core is functioning properly.

When your radiator is cold at the bottom, it`s likely that there`s a debris blockage that`s restricting the flow of hot water to the whole radiator. Usually, the culprit of this particular problem is sludge, debris, rust and other bits of dirt.
​Heater Core and Thermostat Temperature Diagnosis:

190°-210°F Temp. reading at inlet means the thermostat is functioning properly. If temp. at outlet is 10°-25°F cooler than inlet, the heater core is functioning properly.

Start the engine of your car and allow it to warm up for a while. ​Once it reaches the operating temperature, the heater valve automatically allows the coolant to flow through the heater core. This action pushes the air bubble outside. ​Leave the car idle in this state for 15-30 minutes.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

A/C and heat are not working properly. Car blows heat in summer and cool air in winter.
ANSWER : Common causes of no cabin heat include malfunctioning blend door(s) (part of the in-dash ventilation network), a faulty or stuck heater control valve, a plugged heater core, stuck open engine cooling thermostat, collapsed hoses, and low coolant level. The cost to resolve the problem depends on which of the foregoing faults is the cause. If you desire a diagnostic to determine exactly why there is no cabin heat, please request a non functioning cabin heater diagnostic and the responding mechanic will come right to your location and get this resolved for you promptly.

With regard to your air conditioning system, if merely re-charging the system restored normal operation but the a/c ceased to function after a month or so, that scenario typically suggests a leak. Some leaks are really cheap to repair, like if a couple o-rings need to be replaced in system piping but if the leak is at the compressor shaft seal, that repair is more costly. It is not expensive to find the leak and diagnose the system and once the leak is found the mechanic can let you know of the exact cost to repair the leak and re-charge the system. If you desire that service please request an a/c system diagnostic – suspected refrigerant leak and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you

Read Full Q/A … : I have no heat.

Heat inside car stays warm for minute then blows cold until I turn heat off for a minute and try again.
ANSWER : Hi there. The engine always at operating temperature leads me to believe, the thermostat is not the cause, for no heat inside the vehicle. There are several possibilities for no heat inside, the heater control valve is malfunctioning, the heater core is restricted, the temperature blend door actuator is malfunctioning. Replacing components without diagnoses, can be expensive and time consuming without resolution. I recommend having your vehicle’s inoperative heater be diagnosed and repaired by a certified technician, such as one from YourMechanic.

Read Full Q/A … : I have no heat.

Heater not working reliably, is it caused by a bad thermostat?
ANSWER : From what you’ve described, it sounds like you have a stuck open thermostat. I’d recommend replacing the thermostat to see if this is the cause of the slow heat up of the vehicle since it’s a relatively quick repair. In an area like that it sounds like you’ll will need the heat in the winter very badly and as soon as possible. I would also recommend getting a coolant flush as it may help clear any possible blockage in the heater core. To avoid any unnecessary repairs, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose your heating issue and make the necessary repairs.

Read Full Q/A … : I have no heat.

Vehicle at running temp, turn on heat, no heat – stomp on gas, there is heat – ??? 2004 Jeep Liberty
ANSWER : Hello – regarding your lack of heater function unless the engine is revved up a bit, you have a coolant flow issue. This could be caused by a worn water pump (engine might be running warmer than normal?), a partially blocked heater control valve (adjustment problem or failed heater control switch), or clogged cooling system that simply has poor flow. I would recommend an inspection of the heater & cooling system by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

Read Full Q/A … : I have no heat.

Car heat is cold until I add water and over heating with out telling me
ANSWER : Hello, thank you for writing in. There seems to be an issue that we need to take on first and foremost. This is the fact that you are having to add coolant to the system. This means the coolant is leaking either externally (onto the hot engine), or internally (being consumed with the air/fuel mixture). The best way to tell is to simply run the vehicle and watch for the leak. If the engine is consuming the coolant, you are likely seeing white smoke from the exhaust. This is most commonly resolved by replacing the head gasket. Common components to look for an external leak with are the thermostat and the water pump. Both would cause the symptoms you are explaining. Fore more help with the issue, contact our service department to schedule an appointment.

Read Full Q/A … : I have no heat.

My heat and air turns on without a problem but does not blow very hard (heat blows harder than air). Rattling noise.
ANSWER : The heater and the air conditioner both use the same blower motor. However, Nissan does have two separate fuses for the same unit. One of them can be blown. There are also resistors in the system that can fail. There are several electrical tests that can be done, but depending on the condition, it may be more practice to change the entire unit. Due to the age of your vehicle, and the Juke’s history of blower motor issues, it’s very likely a simple fuse issue. These can (for the most part) be visually inspected, and are cheap.

Read Full Q/A … : I have no heat.

Engine is over heating and I’m not getting heat. 2001 Pontiac Grand Am 3.4 V6
ANSWER : Hello – I agree with your diagnosis – a water pump failure is a prime candidate for both overheating and a "no heat from the heater". Lack of water flow will cause both symptoms, and cause damage to the engine in minutes. I would recommend a thorough examination of the cooling system immediately. A mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

Read Full Q/A … : I have no heat.

Car won’t drive after over heating on the highway
ANSWER : Hi there. Most of the time when you overheat this engine it will also cause the transmission to get too hot. When this occurs it can easily cause transmission failure. I would suspect this if the vehicle does not move at all. If it move but is severely lacking power then you either have some serious internal engine damage or a failure in the catalytic converter from the overheating. It sounds like it is the transmission though. I would recommend having a transmission specialist take a look at it.

Read Full Q/A … : I have no heat.