I have central heat and air----during the night the a/c works fine but during the day it blows hot----trying to figure out what's wrong---thanks

You have a dirty outside coil, but you need to clean the entire system which means that you will need to buy two gallons of Alkali Coil Cleaner that you can purchase at any HVAC supply house. On the outside unit you will need to turn off both inside and outside power, then remove top where you can get at both sides of coil and oil fan motor. Your fan motor may be partially frozen which will mean you will need to replace it. Some motors have oil plugs and some don't. You will need a bottle of special oil available at the HVAC parts house ($2.00)that has a long plastic tube. Once you remove the plugs take a piece of stiff wire and poke in holes to make sure they are clear then oil the motor. Wash out coils first with plain water then with 3 gallon plastic pump sprayer on stream, apply a 1 part coil cleaner to three parts water on both sides of coil and wait for it to finish foaming. Rinse off with spray of water, usually from inside to outside, opposite of the normal airflow. Repeat until clean and clean out any leaves and dirt in bottom of unit. Look on steel parts, like a tank called an accumulator that has the larger freon lines attached. If there is any rust on it, which it always is, get a high-quality paint and clean and paint it, or it will rust through causing a $1000 in damage. Prevention is easy.
On inside unit you will have to slide out blower fan by unplugging wires first. You will need a wet-vac, water hose, and coil cleaner to clean these coils. Hopefully, your unit is in a garage. It's harder to clean most inside coils because you have to get at both sides of coil. If you have a problem write me at [email protected]. I hope this helps.

You have a dirty outside coil, but you need to clean the entire system which means that you will need to buy two gallons of Alkali Coil Cleaner that you can purchase at any HVAC supply house. On the outside unit you will need to turn off both inside and outside power, then remove top where you can get at both sides of coil and oil fan motor. Your fan motor may be partially frozen which will mean you will need to replace it. Some motors have oil plugs and some don't. You will need a bottle of special oil available at the HVAC parts house ($2.00)that has a long plastic tube. Once you remove the plugs take a piece of stiff wire and poke in holes to make sure they are clear then oil the motor. Wash out coils first with plain water then with 3 gallon plastic pump sprayer on stream, apply a 1 part coil cleaner to three parts water on both sides of coil and wait for it to finish foaming. Rinse off with spray of water, usually from inside to outside, opposite of the normal airflow. Repeat until clean and clean out any leaves and dirt in bottom of unit. Look on steel parts, like a tank called an accumulator that has the larger freon lines attached. If there is any rust on it, which it always is, get a high-quality paint and clean and paint it, or it will rust through causing a $1000 in damage. Prevention is easy.
On inside unit you will have to slide out blower fan by unplugging wires first. You will need a wet-vac, water hose, and coil cleaner to clean these coils. Hopefully, your unit is in a garage. It's harder to clean most inside coils because you have to get at both sides of coil. If you have a problem write me at [email protected]. I hope this helps.

Thank you ---i will do this today