Cold air, engine light on, & gets hot very quick

Low coolant, if there is an air pocket in the engine it will make it to the heater core. Once there , the air coming out is cold/cool. Once the coolant fills the heater core, it gets hot. If the coolant is fine hot or cold, then have the HVAC system scanned.

this is by design. under load, the computer will deactivate the air conditioning in order to take the load of the compressor off of the engine, thereby getting more power for required acceleration. the a c light will remain illuminated etc, and after you finish accelerating the air conditioning will resume normal operation.

Try changing thermastat.

The heat problem is more than likely the HEATER CONTROL VALVE, it is located in the small hose (1/2" to 3/4") that leads from the engine to the firewall & on into the heater core. You're getting heat because when you turn it off, the heat is travelling backwards into the system & warming it up, until you cool it down again with the heater fan.

A plugged heater core would be the other possibility but I would bypass the valve & even flush the system if it doesn't give you the results you want. That would be the next normal step in resolving the problem.

Easy Fix: Autozone does sell the part, but you may just need to check the vacuum hose that goes to it & turns it on to make sure it's working & not loose or broken. If you want to quickly fix it & not ever have the problem, buy a Prestone Flush and Fill Kit and install the flush "T" where the heater control valve goes and you'll have heat. You may need to install a longer hose to make that work but that's no big issue, just route as needed.

The back-up lights are controlled by a switch and if the fuse isn't blown, that would more than likely be the problem. The type switch depends upon your transmission type. The Back-up Switch mounts on the trans & knows when you are in reverse it allows voltage to pass on to the lights. In. a manual trans, only about 30.00. Either type switch can be bypassed with a toggle or push button type should the cost outweight the benefit.

good luck.

First you have to identify what causes the problem.
To do this you have to:
1) When engine is cold check the level of coolant. If it is low fill it up.
2) Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced.
3) If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is worm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core.
4) If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator.
5) If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest to flush the heater core.

It is most probably the problem with blend door or blend door actuator. But just in case I would suggest to follow the entire procedure:

First you have to identify what causes the problem.
To do this you have to:
1) When engine is cold check the level of coolant. If it is low fill it up.
2) Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced
3) If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is warm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core.
4) If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator.
5) If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest flushing the heater core.

First you have to identify what causes the problem.
To do this you have to:
1) When engine is cold check the level of coolant. If it is low fill it up.
2) Start engine and check if engine reaches regular temperature. If your engine is not heated enough it means your thermostat does not work properly and should be replaced.
3) If engine temperature is normal, then check the temperature of pipes that go to/from heater core. These pipes are located up the fire wall (easier access is from the passenger side). If pipe/pipes are cold (even engine is warm) it means you heater core is plugged and should be flushed. Keep in mind, flushing the whole cooling system is different from flushing heater core.
4) If pipe/pipes are hot/warm, turn off the fan, switch controller to the hot position, wait for 3-4 minutes and turn on the fan. Note if the cold air blows first or warm air blows first but it cools down in 5-10 seconds. If the air blows cold than it is most probably the problem with blend door or blend door actuator.
5) If air blows warm first and then cools down, then while running engine and remaining the transmission in PARKING position, press on the gas pedal until your engine reaches 3,000 RPM. Check if your heater blows warm/hot air. If it does, then your water pump does not work properly and should be replaced. If the air still cold, I would suggest flushing the heater core.

Here's the thing. The ECU will shut down AC if the engine temperature is too hot. If the coolant temperature sensor is malfunctioning (lying to the ECU) telling it that the temperature is hotter than it actually is, the computer will turn the AC OFF.

The coolant temp sensor sends signal to the ECU and the ECU adjusts the idle RPM. When the coolant is cold, the engine requires more fuel to sustain idle with thick oil (oil gets thicker & more viscous when cold). This makes the engine to idle at faster RPM but it should settle down to 850 RPM or so after the coolant warms up. The sensor is nothing but a thermistor; a device that changes electrical resistance according to the coolant temperature.