The immediate effect of price controls or any government intervention upon the market is shortage of goods. Price controls discourage production just when it is needed most. The economy approaches full socialization. Rent control is the easiest way to destroy a city besides bombing it.
A maximum price control prohibits all exchanges of a good above a certain price, with the controlled price being below the market equilibrium price. A minimum price control prohibits exchanges below a certain price.
The fourth of ten lectures from Joseph Salerno's Introduction to Austrian Economic Analysis seminar.