Most American made cars do have a relay on the air conditioner. The relay is usually located underneath the hood. It could be on the fire wall, inner fender or some place on the motor. European and Asian Cars also have A/C relays. You can find them on the electrical schematic diagrams. For example, VW diesels of the mid-1980's have one on the radiator, and one in the relay panel under the dash on the left had side. Nissan Maxima's of the mid 1990's have two also, one in the relay box under the hood, and another in the row of four relays to the right of the fuse panel on the left hand side of the dash.
The 1999 Acura air-conditioner relay switch can be found in the fuse box. The air conditioner relay switch will be in the third column, second from the top.
The 1991 Ford Explorer air conditioning relay switch can be found on the firewall in the engine compartment. The air conditioning relay switch will be on the drivers side of the firewall.
The 1992 Chevrolet Suburban air conditioner compressor relay switch can be found in the fuse box. The air conditioning compressor relay switch will be labeled as such.
The 2000 Chevrolet S 10 pickup truck air conditioning relay switch can be found in the fuse box. The relay switch will be in the third column.
Without knowing the make and model this is difficult to say
The air conditioning compressor clutch relay is located on the bottom of the air conditioner compressor. The relay switch will be labeled.
which is the air conditioner relay on a 99 ford ranger
You should be able to switch the relay with the horn relay and then check to see if the horn works.
My guess is the system is low on freon being 11 years old.
You can find the air conditioner fuse for your 1990 Ford in the fuse box. The fuse box is located beneath the drivers side dashboard. The fuse box will also contain an air conditioner relay switch.
switch, relay or blower motor problem as a guess.