Compressor cycles on for about 7 seconds then stops for 5 secs, then repeats. The air is not cold at all. (1997 F150 4.6 Ltr.) Is there a relay failure somewhere?

 

Nope, that means you have no or low pressure in your system from a leak. Cheapo can might get you by, but if it has leak, it will leak again.

Might want to also pay attention to the model year forum you are posting in as well.

Welcome to the forum.

Adrianspeeder

 

Take it to a pro.

 

check pressures with a/c system turned off . on a good sunny 85-90 degree day your pressure should be 90-100 psi. if not, your low on freon. if your pressure is good replace pressure switch on receiver/drier.