Why does my heater keep turning on and off it was fine til a friend srewed with it now it wont stop doing it no matter what I do please help

Could be damaged loom feeding the ignition/start circduit or fuse blown maybe.
A mechanic will know this.

Good Day ,

You have a great equipment , this might be of help
https://youtu.be/BtoGAeWP5-4

or might try this

Probably the cruise servo to sensitive to load will need to replace,when you shut off it resets til the next time.

On the steering wheel is the hand controls. Scanning is stuck because of dirt or something. Push the buttons, blow out dirt, wash it off. Mine worked fine after that. (How annoying up til then though. Hope this works. Russ Werth Bowman ND

I found these instructions when my heater suddenly stopped working. Start car, while car is parked turn temperature to 75. Hold down the floor, defrost/floor and the defrost buttons. Wait til the temp light starts blinking, release. It will blink for a while and either recalibrate and be fine like mine or you could get 1 of 16 different trouble codes. Hope this helps. ;p ~Redmoon

BLOW OUT THE BACK OF THE MOTOR WITH COMPRESSED AIR. THERE IS TRASH IN THE START SWITCH , AND IF YOUR LUCKY IT WILL FIRE BACK UP. IF YOUR IN THE LONGWOOD FL AREA I DO THIS FOR FREE FOR MY ABOVE GROUND POOL CUSTOMERS
OTHER SHOPS MAY DO IT ALSO, JUST CALL AND ASK
JAY THE POOL PUMP MOTOR REPAIR GUY IN LONGWOOD FL 32750. PLESE VOTE YES OR NO IF I WAS OF HELP

maybe ur thermostat

I can only think of two other things that could cause it not to get as hot as it should, Either there is a restriction in the heater control valve or the heater core is stopped up. If you drain your coolant and ran some radiator flush through it it might help. If I have help you please rate me... Thanks

give the battery a full charge....un clip the air filter housing and leave it resting in place, put your foot to the floor on the gas pedal and keep cranking til it starts up,dont release the ignition key til it fires up,it will pop and bang and then when it fires up will smoke for a little bit (couple of mins) and then it will be fine.
If that doesnt work you will have to remove all 8 plugs,clean them,pour about 2 teaspoons in each cylinder before replacing plugs then do the same as above.
What happens with these engines is the cylinders get a bit too much fuel in them and it washes the oil away down the bores thus losing comression so it wont start.Instead of starting it up and switching it off briefly,let it run a bit and then give it a little rev before switching off...hope this helps

it is a technical fault. check wit a cumputer repairs technichian and ask for a quote on this problem.