My antenna does not go down anymore. Is it

Try and clean the entire motor and antenna setup.

Usually the antenna is operated by a spool and a reel of stuff like white nylon or plastic "wire".
When you push or turn the switch or when you turn on the radio, however the antenna is supposed to go up, the spool will turn in the direction to extend the string and push the antenna up.
When you turn off the radio, or move the switch to "retract", the spool will turn and wind up the string and pull the antenna down. These strings often break, usually they only last about 5 years.
The motor you seek is inside the fender or the trunk, as the case may be, and it is hidden behind the inner fender shield or in the trunk, behind the inner trunk panel.
The motor is hidden to prevent snow, ice, water, and dirt from ruining it.
Be blessed.

first of all, is your radio factory or aftermarket? If its factory the you probably have a bad ground or a short in the radio power to antenna. If its after market, then the remote antenna wire is hooked up wrong. Check to make sure the antenna wire is hooked up to the antenna. Good luck

tge antenna switch is probably installed backwards

It is supposed to shut down when it overheats, that is a safety precaution to save further damage. You fix the overheating problem and it won't shut down anymore.

i have a 1990 iroc-z and i replaced the radio with an aftermarket radio. when i replaced the factory radio i had to do a little manuvering of the wires because of the alarm i had installed. the antenna wire is supposed to be ran under the PASSENGER side i dont understand why they are under the driver side.

I assume that the power antenna unit is an original equipment unit, if so.
1. Does it run for about a minute then stop? If this is the case, your antenna shaft needs to be replaced. This is a very simple procedure that your local radio install shop can do for you in about 20 minutes.
2. If the motor never shuts off as long as the key is on, you probably have a defective relay on the antenna motor. At this point you need to replace the entire unit. A job that can be a bit pricey because of the price of the unit itself. A cheeper fix is to replace the power antenna with a manually telescopic unit, (no motor), or a fixed unit, (doesn't go down). If you opt for the latter, remember to unscrew or lower the antenna in automatic car washes!

You need to pull the fuse for the antenna or just unplug it. It has a fairly ridgid plastic wire that pushes the antenna up and down. Works fine until the wire breaks then it rolls up (antenna down) but it never increases resistance because the antenna never comes down , it's like a fishing reel when the lure breaks off, so the motor thinks that the antenna is still coming down and it will run and run and run trying to do it's job. Your lucky it stuck up and not down. If you want your antenna to go up and down again you'll have to buy and install a new one.

this is normal the power antenna gets power from the radio and unless the radio is shut off either from powering it down or turning off the car it will stay up. if it is an aftermarket stereo and is staying up when you are on cd's check to make sure that your antenna is hooked to the antenna output on the radio and not the system remote as the system remote is hot any time the radio is powered to run amplifiers.

Sounds like you just have a bad connection at radio power wire. Check radio fuse first to make sure it's o.k. but then you'll have to get someone to trace power wire to back of radio & check connections.